Field Release of the 

Arundo Scale, 

Rhizaspidiotus donacis

(Hemiptera:

Diaspididae), an Insect 

for Biological Control of 

Arundo donax (Poaceae) 

in the Continental 

United States

Environmental Assessment,

December 2010

United States

Department of 

Agriculture

Marketing and 

Regulatory 

Programs

Animal and 

Plant Health 

Inspection 

Service
Field Release of the Arundo 

Scale, Rhizaspidiotus donacis

(Hemiptera: Diaspididae), an 

Insect for Biological Control of 

Arundo donax (Poaceae) in the 

Continental United States

 

Environmental Assessment,

December 2010

Agency Contact:

Shirley Wager-Page, Branch Chief

Pest Permitting

Plant Protection and Quarantine

Animal and Plant Health Inspection Service

U.S. Department of Agriculture

4700 River Road, Unit 133

Riverdale, MD 20737–1236

__________________________________________________________

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__________________________________________________________

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Table of Contents

I. Purpose and Need for the Proposed Action......................... 1

II. Alternatives.............................................................................. 2

III. Affected Environment............................................................. 5

IV. Environmental Consequences ............................................ 11

V. Other Issues .......................................................................... 25

VI. Agencies, Organizations, and Persons Consulted............ 26

VII. References ............................................................................ 27

Appendix A. Host Plant Test List for R. donacis

Appendix B. Results of No-Choice Host Range Tests for 

Rhizaspidiotus donacis

Appendix C. Results of No-Choice Host Range Tests for 

Rhizaspidiotus donacis in which 1,000 Crawlers 

Were Released Per Plant
1

I. Purpose and Need for the Proposed 

Action

The U.S. Department of Agriculture (USDA), Animal and Plant Health 

Inspection Service (APHIS), Plant Protection and Quarantine (PPQ), Pest 

Permitting Branch (PPB) is proposing to issue permits for release of an 

armored scale insect, Rhizaspidiotus donacis (Leonardi) (Hemiptera: 

Diaspididae). The agent would be used by the applicant for the biological 

control of Arundo donax L. (giant reed, carrizo cane) in the continental 

United States. Before permits are issued for release of Rhizaspidiotus 

donacis (R. donacis), the APHIS–PPQ PPB must analyze the potential 

impacts of the release of this agent into the continental United States.

This environmental assessment1(EA) has been prepared, consistent 

with USDA–APHIS' National Environmental Policy Act (NEPA) 

implementing procedures (Title 7 of the Code of Federal Regulations 

(CFR) part 372). It examines the potential effects on the quality of the 

human environment that may be associated with the release of R. donacis

to control infestations of Arundo donax (A. donax) within the continental 

United States. This EA considers the potential effects of the proposed 

action and its alternatives, including no action.

The applicant’s purpose for releasing R. donacis is to reduce the severity 

of infestations of A. donax in the United States. It is an extremely invasive 

weed of riparian habitats and irrigation canals of the Rio Grande River 

Basin and the Southwestern United States. A. donax is native to the Old 

World from the Iberian Peninsula of Europe to south Asia, including 

North Africa and the Arabian Peninsula. It has been cultivated in the Old 

World for thousands of years and has been widely introduced around the 

world as an ornamental and for its fiber uses. It was introduced into North 

America in the early 1500s by the Spanish for its fiber uses and quickly 

became naturalized. It is now found throughout the southern half of the 

United States from Maryland to California; however, it is most invasive 

along muddy banks of creeks and rivers in the Southwestern United States.

A. donax infestations in riparian habitats lead to loss of biodiversity,

stream bank erosion, altered channel morphology, damage to bridges,

increased costs for chemical and mechanical control along transportation 

corridors, and impediment of law enforcement activities on the 

international border. Additionally, this invasive weed competes for water 

resources in an arid region where these resources are critical to the 

environment, agriculture, and municipal users. A. donax is a severe threat 

 

1

Regulations implementing the National Environmental Policy Act of 1969 (43 United States Code 

4321 et seq.) provide that an environmental assessment ―shall include brief discussions of the need 

for the proposal, of alternatives as required by section 102(2)(E), of the environmental impacts of the 

proposed action and alternatives, and a listing of agencies and persons consulted‖ 40 CFR § 1508.9.
2

to riparian areas where it displaces native plants and animals by forming 

massive stands that pose a wildfire threat (Frandsen and Jackson, 1994). It 

may reduce stream navigability (Dudley, 2000). It consumes excessive 

amounts of water and competes for water resources in an arid region prone 

to perennial droughts. Under optimum conditions, it can attain growth 

rates of 0.7 meters (m) per week or 10 centimeters (cm) per day, putting it 

among the fastest growing plants (Perdue, 1958; Bell, 1997). Under ideal 

growth conditions, A. donax can produce more than 20 metric tons of 

above-ground dry mass per hectare (Perdue, 1958). 

Existing A. donax management options are expensive, temporary, and

have nontarget impacts. In addition, release of R. donacis is expected to 

augment the impact of another biological control organism previously 

released against A. donax. For these reasons, the applicant has a need to 

release R. donacis into the environment, an effective, host- specific, 

biological control organism for the control of A. donax. 

II. Alternatives

This section will explain the two alternatives available to the APHIS–

PPQ–PPB—no action (no issuance of permits) and issuance of permits for 

environmental release of R. donacis. Although APHIS’ alternatives are 

limited to a decision on whether to issue permits for release of R. donacis, 

other methods available for control of A. donax are also described. These 

control methods are not decisions to be made by the APHIS–PPQ–PPB 

and their use is likely to continue whether or not permits are issued for 

environmental release of R. donacis, depending on the efficacy of 

R. donacis to control A. donax. These are methods presently being used to 

control A. donax by public and private concerns. 

A third alternative was considered but will not be analyzed further. Under 

this third alternative, the APHIS–PPQ–PPB would have issued permits for 

the field release of R. donacis, but the permits would contain special 

provisions or requirements concerning release procedures or mitigating 

measures. No issues have been raised that would indicate that special 

provisions or requirements are necessary.

A. No Action

Under the no action alternative, the APHIS–PPQ–PPB would not issue 

permits for the field release of R. donacis for the control of A. donax. The 

release of this biological control agent would not take place. The 

following methods are presently being used to control A. donax. These 

methods will continue under the ―no action‖ alternative, and will likely 

continue even if permits are issued for release of R. donacis.
3

A. donax may be controlled using herbicides. Glyphosate is a broadspectrum herbicide that is commonly used on a variety of wetland and 

aquatic plants, such as water hyacinth (Eichhornia crassipes), giant 

salvinia (Salvinia molesta), saltcedar (Tamarix spp.), and others, including

A. donax. Glyphosate has proven to be effective against A. donax (Finn 

and Minnesang, 1990; USDA–Forest Service, 1993). One of the reasons 

for its effectiveness is that glyphosate is a systemic herbicide and, when 

used at appropriate times, it is translocated to the roots, killing the entire 

plant. A number of techniques were developed for its use, including

1) use as a foliar spray, 2) cutting plant stems and spraying, or painting the 

herbicide on the surface of the cut, and 3) cutting stems, letting plants resprout, and treating the re-sprouts with herbicide. 

Additionally, an herbicide (Habitat®) with another active ingredient, 

imazapyr, has been developed and registered for use on A. donax. In 

general, Habitat® requires one to two applications and control may be 

achieved for several years. Removal of dead canes may be necessary if 

stem densities are great enough to inhibit recovery of native vegetation 

after treatment.

Mechanical methods of A. donax control include use of prescribed fire, 

heavy machinery (e.g. bulldozer, Hydro-axe), hand-cutting, chipper, etc.).

Removal of dead canes may be necessary if there is a possibility that cut 

vegetation might create a flood hazard during high water events or if 

biomass density is great enough to inhibit recovery of native vegetation. 

Burning is a cost-effective way of removing biomass if it does not threaten 

native vegetation. Another, but more costly, means of removal is 

chipping. Equipment and labor are expensive relative to other forms of 

removal; however, the small dry chips that are produced pose little threat 

in terms of regeneration, and they do not form debris dams. Biomass 

removal by vehicle is expensive and, generally, not preferred due to its 

lack of cost-effectiveness. The use of heavy machinery, such as the 

Hydro-axe, is extremely expensive and slow, cutting only about 3 to 

4 acres per day (Bell, 1997).

The Arundo wasp, Tetramesa romana Walker (Hymenoptera: 

Eurytomidae) was approved for release in April 2009. It currently occurs 

in Texas and California. However, it is not expected that Tetramesa 

romana (T. romana) alone will completely control A. donax. The stem 

galling of A. donax caused by T. romana results in stunted stems and 

sometimes death of the stems. When both T. romana and R. donacis are 

present, A. donax plants become severely stressed with extreme stunting 

and virtually no leaf production.

1. Chemical 

Control

2. Mechanical 

Control 

3. Biological 

Control
4

B. Issue Permits for Environmental Release of 

R. donacis

Under this alternative, the APHIS–PPQ–PPB would issue permits upon 

request and after evaluation of each application for the field release of the 

armored scale insect R. donacis against A. donax. These permits would 

contain no special provisions or requirements concerning release 

procedures or mitigating measures.

Biological Control Agent Information

a. Taxonomy 

Order: Hemiptera

Family: Diaspididae

Genus: Rhizaspidiotus 

Species: donacis (Leonardi)

Common name: Arundo scale

b. Geographical Range of R. donacis

R. donacis is limited to mild Mediterranean climates of Europe (Portugal, 

Spain, southeastern France, and southern Italy. It is not known whether 

R. donacis will be able to establish throughout the range of A. donax, but it 

is likely to be a subset of this range. It appears likely that R. donacis will 

not establish north of USDA’s Plant Hardiness Zone 8b (Goolsby, 2009). 

This corresponds to areas with minimum average temperatures of 10 to 

20 °F, such as Gainesville, Florida, and Charleston, South Carolina.

c. Life History of R. donacis

The life cycle of R. donacis follows the generalized diaspidid (armored 

scale insect) life cycle described by Koteja (1990). The life cycle can be 

summarized as follows: mobile crawlers emerge from the body of the 

female, exit the protective scale cover or armor, and disperse to new plant

tissue. Crawlers settle on leaf collars, stem nodes, or rhizomes

(horizontal, usually underground stem that often sends out roots and 

shoots from its nodes) to insert mouthparts and begin feeding. Crawlers 

molt to the second instar, called a white cap. Second instars are immobile, 

and continue to grow in size and add concentric layers to their scale cover. 

The late second instar female scale is inseminated by the mobile, winged, 

male scale. The female scale molts to the adult instar. The immobile 
5

adult female continues to feed and develop for several months before 

producing live crawlers. 

The male scale has a different life cycle. Male crawlers molt to the second 

instar. At the end of the second instar, they emerge as winged adults at 

precisely the right time to mate with the late second instar, immobile

females. 

Based on observations of native field collections of R. donacis, many 

crawlers settle on rhizomes, but only if the soil substrate is suitable (dry 

and sandy/rocky substrates are most conducive to crawler survival) 

(Goolsby, 2009). Settled crawlers insert their mouthparts into the plant 

and feed on plant cell fluids. 

The timing of the molts from first to second nymphal instar and from 

second instar to adult, and survival through these transitions varies among 

diaspidid species and within species seasonally (Kuwana, 1923; Carroll 

and Luck, 1984; Polavarapu et al., 2000); however, the overall duration of 

immature development for R. donacis is consistent with studies on other 

species that are capable of producing more than one generation per year. 

Observations of populations collected in the native range suggest that 

R. donacis completes two generations per year in the field, although the 

generations may differ in length (Malumphy, 1997). However, Goolsby 

(2009) observed only one generation per year for R. donacis in Italy. The 

length of time for one life cycle of R. donacis is 6 to 6.5 months (Goolsby, 

2009). 

III. Affected Environment

A. donax is a bamboo-like perennial that grows to 8 m tall, with thick, 

well-developed rhizomes. Plants are typically terrestrial but tolerate 

periodic flooding. In California, from the late 1700s to early 1800s, 

A. donax was often planted for erosion control in flood channels and as 

wind breaks. More recently, it has become problematic in riparian 

corridors throughout the Southwestern United States and northern Mexico. 

Dense, impenetrable stands typically develop, which often displace native 

vegetation, diminish wildlife habitat, and increase flooding and siltation in 

natural areas. A. donax is also adapted to a periodic fire regime. The 

canes are readily flammable throughout much of the year, and the 

presence of A. donax increases the susceptibility of riparian corridors to 

fire. Large stands of A. donax can significantly increase water loss from 

underground aquifers in semi-arid regions due to a high evapotranspiration 

rate, which is estimated at roughly three times greater than that of the 

native riparian vegetation. A. donax is cultivated as an ornamental, for 

industrial cellulose, and to produce reeds for woodwind instruments. It is 
6

an alternate host for beet western yellows virus, sugarcane mosaic virus, 

and maize dwarf mosaic virus. 

A. donax reproduces vegetatively from rhizomes and stem fragments. 

Fragments disperse with water, mud, and human activities. Under optimal 

conditions, plants grow and spread rapidly during the warm season. Intact 

rhizomes buried under about 1 to 3 m of silt can develop new shoots. 

Under experimental conditions, rhizome fragments readily develop new 

shoots from a depth of 25 cm, whereas stem fragments mostly re-sprout 

from a depth less than 10 cm. Viable seed has not been observed in North 

America or in the native range (DiTomaso and Healy, 2003).

A. Areas Affected by A. donax

A. donax is native to Europe from the central Atlantic coast of Portugal, 

inland along the major rivers of the Iberian Peninsula, along the 

Mediterranean coast from Spain to Greece, including the warmer parts of 

the Adriatic Coast. In north Africa along the Mediterranean, the 

populations are discontinuous from the Western Sahara, Morocco, and 

Algeria, to the Arabian Peninsula. Remote populations are known from 

the Sahara in stable oases. Populations in China are not considered to be 

native. In addition to A. donax, other Arundo species are native to the 

Mediterranean, including A. plinii Turra, A. collina Tenore, and 

A. mediterranea (Danin et al., 2002; Danin, 2004; Danin et al., 2006). The 

only other known Arundo species outside of the Mediterranean is 

A. formosana in Taiwan.

A. donax has a nearly worldwide distribution in tropical to warmtemperate regions. In the United States, it is invasive from northern 

California across the Southwestern and Southeastern United States to 

Maryland. It is widely distributed in Mexico, and Central and South 

America. The most severe infestations in the United States are in Arizona, 

California, and Texas, especially the Santa Ana River Basin and Rio 

Grande Basin.

A. donax is well established in North America, although it continues to 

spread into new areas. Figure 1 shows the areas that are climatically 

suitable based on CLIMEX

2

parameters from Europe. While the predicted 

CLIMEX distribution broadly agrees with the actual distribution, A. donax

has naturalized further north. It has been documented in South Bend, 

Indiana, and Coeur’d’alene, Idaho.

Some of the most severely infested areas are in the Rio Grande Basin and 

in the coastal rivers of southern California. A continuous stand of 

 

2

CLIMEX is ―software to predict the effects of climate on species. (See 

http://www.climatemodel.com/climex.htm.)

1. Native and 

Introduced 

Range

2. Present and 

Potential 

Distribution 

in North 

America 
7

A. donax occurs from just south of Laredo to Del Rio, Texas. The swath 

of A. donax is nearly 0.5 miles wide along this stretch of the Rio Grande

River. Further upriver, near Big Bend National Park, stands of A. donax

are increasing in size and density. Heavy rains during the summer of 2007 

stimulated new growth, and flood waters distributed propagules 

downstream. Aerial surveys conducted by USDA researchers in the fall of 

2007 revealed much more A. donax than had been previously seen in the 

2002 surveys (Goolsby, 2008).

The spread of A. donax into new areas appears to be from earthmoving 

equipment and roadway mowers (Goolsby, 2008). Once established in a 

watershed, rhizomes and canes move downstream during flood events to 

establish new stands. The movement of A. donax for biofuel trials also 

presents another means of spread. The State of Florida evaluated a request 

to plant A. donax on a plantation south of Lake Okeechobee. Concerns 

presented by the Florida Exotic Pest Plant Council were that it could not 

be contained from entering the Everglades following high rainfall events,

such as major hurricanes (Florida Native Plant Society, 2006). This 

business venture is no longer planned for Florida, but instead is being 

considered for St. Augustine County in east Texas (Loder, 2007).

 

Figure 1. Areas in North America (red to pink) that are climatically suitable for 

Arundo donax. 

A. donax typically grows on sites with a low slope in riparian areas, 

floodplains, ditches, and irrigation canals. In the Eastern United States, 

with average rainfall above 30 inches, it can grow in upland sites, such as 

windbreaks or in ornamental settings. A. donax occurs in a wide range of 

soils types with variable fertility, but grows best in well-drained, moist 

soils. Plants tolerate some salinity and extended periods of drought;

however, they do not survive in areas with prolonged or regular periods of 

freezing temperatures (DiTomaso and Healy, 2003). 

3. Habitat 
8

B. Plants Related to A. donax and Their Distribution

Taxonomically Related Plants 

Grass species (Poaceae) that were used in testing the specificity of 

R. donacis to A. donax are listed below and in appendix A. Information 

regarding plants taxonomically related to A. donax is included in this 

document because native plant species which are closely related to 

A. donax have the most potential to be attacked by R. donacis.

Andropogon glomeratus (Walter) Britton et al. (bushy bluestem) is native 

to the Southern United States and north to New York and south to 

northern South America.

Aristida purpurea Nutt. var. longiseta (Steud.) Vasey (red threeawn) is 

native from western Canada to northern Mexico and grows in well-drained 

soils.

Arundinaria gigantea (Walter) Muhl. (giant cane) is native to the 

Southeastern United States.

Arundo formosana Hack. (fountain reed), a smaller relative of A. donax, is 

native to Taiwan, the Ryukyu Islands of Japan, and the Philippines. It is a 

very minor ornamental plant in northern California.

Bouteloua hirsuta Lag. (hairy grama) is a bunchgrass native to most of the 

United States and south to Guatemala. 

Chasmanthium latifolium (Michx.) Yates (inland sea oats) is native from 

the Middle Atlantic States of the United States west to Texas and grows 

along waterways and in moist woods.

Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn. (pampas 

grass) is an ornamental grass native to Brazil and the southern part of 

South America. Pampas grass has been planted in the southeast and 

southwest of the United States, and is invasive in some areas.

Cynodon dactylon (L.) Pers. (Bermuda grass) is a pasture and turf grass 

native to Africa that now grows worldwide except in the coldest and driest 

areas.

Cyperus articulatus L. (jointed flatsedge) is an obligate wetland plant 

native to the area from South Carolina and Florida to Texas, and south to 

South America, as well as Africa and Asia.
9

Danthonia spicata (L.) P. Beauv. ex Roem. & Schult. (poverty oatgrass) is 

native throughout most of North America from the subarctic through 

central Mexico.

Dichanthelium acuminatum (Sw.) Gould and Clark (tapered rosette grass) 

is native to most of North America and south to Colombia and Ecuador, as 

well as in the Caribbean. It is endangered in Tennessee. 

Digitaria cognata (Schult.) Pilg (fall witchgrass) is native from Ontario, 

Canada, through the Eastern half of the United States and into northern 

Mexico.

Elymus virginicus L. (Virginia wildrye) is native throughout most of 

Canada and the United States.

Eragrostis intermedia Hitchc. (plains lovegrass) is a native grass ranging 

from the Southern United States to Costa Rica. 

Eragrostis spectablilis (Pursh) Steud. (purple lovegrass) is native to 

southeastern Canada, the Eastern two-thirds of the United States, and 

south to Belize.

Eriocaulon decangulare L. (tenangle pipewort) grows in moist to wet soils 

from the mid-Atlantic region of the United States through the Southeast,

and Mexico to Nicaragua. It is endangered in Tennessee.

Leptochloa dubia (Kunth) Nees (green sprangletop) is a native to Florida,

Oklahoma to Arizona, and south through Mexico. It is best adapted to 

deep sandy soils in Florida, and to rocky hills and canyons in the rest of its 

range.

Leptochloa fusca (L.) Kunth subsp. uninervia (J. Presl) N. Snow (=L. 

uninervia) (red sprangletop) is native to the southern half of the 

United States and much of Mexico, the Caribbean, and Central and South 

America. This species is now an invasive species in rice fields in Spain 

and Italy.

Leptochloa panicea (A. Retzius) J. Ohwi subsp. brachiata (=L. filiformis) 

(Mexican sprangletop) is native to the Southern half of the United States

and much of Mexico, the Caribbean, and Central and South America. It 

has naturalized in Africa and Australia.

Leptochloa virgata (L.) P. Beauv. (tropic sprangletop) is native to Texas 

and Florida in the United States, and also to Tamaulipas and Veracruz, 

Mexico, as well as to much of Central and South America and the 

Caribbean.
10

Molinia caerulea (L.) Moench (purple moor grass) is a perennial bunch 

grass native to temperate areas of Eurasia. It has been introduced as an 

ornamental to northeastern Canada and the United States where it has 

invaded damp areas.

Muhlenbergia capillaris (Lam.) Trim. (hairawn muhly) is a bunchgrass 

native to the Southeastern United States and the Bahamas.

Oryza sativa L. (rice) is of Asian origin and is grown in tropical, 

subtropical, and warm-temperate areas around the world.

Panicum amarum Elliot. (bitter panicgrass) is native to coastal dunes 

along the Atlantic and gulf coasts of the United States and the gulf coast of 

northern Mexico, as well as in swamp edges and wet sandy soils in this 

range.

Panicum hirsutum Sw. (hairy panicum) is a native that grows from 

southern Texas to Argentina and in the Caribbean.

Panicum virgatum L. (switchgrass) is a native that grows mainly east of 

the Rocky Mountains from southern Canada through Central America and 

in Cuba.

Pennisetum ciliare (L.) Link (buffelgrass) is native to Africa, Western 

Asia, and India. It has been introduced to and become highly invasive in 

the Southern United States and Mexico and elsewhere as a forage crop.

Phragmites australis (Cav.) Trin. ex Steud. (common reed) is similar in 

appearance and habitat to A. donax. P. australis is found nearly 

worldwide in temperate and tropical wet habitats. An introduced ecotype 

from Europe is invading northeastern North America. This exotic ecotype 

is the target of a biological control program in the United States.

Saccharum officinarum L. (sugarcane) is grown in the Southeastern 

United States, as well as in other tropical/subtropical regions throughout 

the world. It is native to tropical Asia and Oceania.

Schizachyrium scoparium (Michx.) Nash (little bluestem) is native to most 

of Canada, the United States, and northern Mexico.

Schoenoplectus maritimus (L.) Lye (alkali bulrush) grows from Canada 

into South America, as well as in Africa, Eurasia, and Oceania. It may 

actually be native to Eurasia.

Sorghum bicolor (L.) Moench (sorghum) is a native of Africa that is 

grown through much of the world.
11

Spartina alterniflora (S. alterniflora) Loisel. (smooth cordgrass) is an 

obligate wetland species native to saltmarshes along the Atlantic coast of 

Canada, the Atlantic and gulf coasts of the United States, the Caribbean, 

and northern South America to Uruguay. It is an introduced invasive 

along the Pacific coast of California, Oregon, and Washington, as well as 

in Western Europe and New Zealand.

Spartina spartinae (Trin.) Merr. ex Hitchc. (Gulf cordgrass) is a native 

bunch grass that grows mainly along the Atlantic coast of Florida, the gulf 

coast of the United States, and Mexico to Costa Rica. In South America it 

is native to Venezuela, Argentina, and Paraguay.

Sporobolus wrightii Munro ex Scribn. (alkali sacaton) is a native growing 

in Texas and Oklahoma, west to California, and south to central Mexico.

Tridens albescens (Vasey) Wooton & Standl. (white tridens) is native to 

Texas, Oklahoma, Kansas, New Mexico, Arizona, and northern Mexico.

Tripsacum dactyloides (L.) L. (eastern gamagrass) is native to the Eastern 

and Central United States, and south through Mexico to northern South 

America.

Triticum aestivum L. (wheat) originated in central and Western Asia, but 

is planted in many of the temperate areas of the world.

Typha domingensis Pers. (narrowleaf cattail) is an obligate wetland plant 

native to the lower two-thirds of the United States and south into much of 

South America. It grows through much of the tropics and warm temperate 

areas.

Uniola paniculata L. (sea oats) is a native that grows on sand dunes along 

the coast from Maryland to Veracruz, Mexico, as well as in the Bahamas 

and Cuba.

Zea mays L. (corn) is native to Mexico but is grown through much of the 

world.

 

IV. Environmental Consequences

A. No Action

a. Beneficial Uses 

A. donax is grown for woodwind reeds, although there is currently no 

commercial production in North America (Perdue, 1958; Obataya and

Norimoto, 1995). The highest quality reeds come from the native range in 

1. Impact of 

Spread of 

Arundo donax 
12

Europe. It is also used in basketry, for fishing rods, livestock fodder, and 

medicine. Currently, the most significant use of this plant is its proposed 

use as biofuel (Szabo et al., 1996). There are a few small-scale research 

plantings of A. donax in Texas and Georgia. Use of A. donax as a biofuel 

has sparked considerable controversy in Florida, which may have caused 

entrepreneurs to consider establishing an Arundo plantation in Texas 

(Florida Native Plant Society, 2006). The use of invasive species as 

biofuels is considered to be extremely risky. Raghu et al. (2006) presents 

the case that the long-term environmental consequences of using invasive 

species will far outweigh the short-term gains for energy use. USDA 

research on biofuels precludes the use of Federal dollars for research on 

invasive plants.

b. Nontarget Plants 

Nontarget plants growing in riparian areas are severely impacted by 

A. donax throughout North America. A. donax grows in dense stands that 

prevent normal regeneration of native riparian vegetation. In many areas, 

A. donax is burned yearly to keep standing vegetation to a minimum. In 

other areas, accidental wildfires enter riparian zones infested with 

A. donax damaging riparian plants. In both cases native plants, especially 

trees that are not fire adapted, are killed by the hot fires. A. donax

survives the wildfires due to its extensive below-ground rhizomes. It 

regrows quickly after fires, shading out emerging seedlings, thus 

increasing its dominance over native riparian vegetation.

c. Ecosystem Function

Widespread effects of A. donax on ecosystems have been documented on 

several continents, including Australia, North America, Oceania, and 

Africa. The Global Invasive Species Database lists A. donax as one of the 

worst 100 invaders (see 

http://www.issg.org/database/species/ecology.asp?si=112). A. donax can 

increase sediment deposition in natural and manmade channels resulting in 

reduced channel depth and greater flooding (Frandsen and Jackson, 1994). 

In addition, during flooding, debris dams of A. donax may collect adjacent 

to flood control structures, bridges, and culverts, exacerbating flooding 

(Frandsen and Jackson, 1994). A. donax produces profuse quantities of 

biomass (Perdue, 1958; Sharma et al., 1998; Spencer et al., 2006) that are 

quite flammable at the end of the growing season. As a result, it has 

changed control of ecosystem processes in some Californian riparian 

zones from flood-regulated to fire-regulated (Rieger and Kreager, 1989). 

d. Protected Species

A. donax threatens most native plants and, thereby, native wildlife 

growing in the same habitat. The least Bell’s vireo, southwestern willow
13

flycatcher, and yellow-billed cuckoo are negatively impacted by A. donax

because it does not provide the structural habitat and food sources that 

native vegetation provides (Frandsen and Jackson, 1994; Dudley and 

Collins, 1995). In Sonoma Creek, California, A. donax was associated 

with about 50 percent of the reduction in the total number and biomass of 

arthropods that were found on native vegetation (Herrera and Dudley,

2003). Protected aquatic species (such as the arroyo toad, red-legged frog, 

western pond turtle, Santa Ana sucker, arroyo chub, unarmored threespined stickleback, tidewater goby, and steelhead trout) are negatively 

affected by A. donax because it provides little shade over streams and 

leads to increased water temperatures that are unsuitable for wildlife 

(Hoshovsky, 1988).

e. Human Health

There are a few reports of allergies to Arundo pollen. It is listed on 

www.pollenlibrary.com as a moderate allergen.

f. Water Usage

Large stands of A. donax can increase water loss from underground 

aquifers in semi-arid regions due to a high evapotranspiration rate, which 

is estimated at roughly 3 times greater than that of the native riparian 

vegetation. A. donax consumes an estimated 56,200 acre-feet of water 

annually from the Santa Ana River alone (Zembal, 2007). 

The continued use of chemical herbicides, and mechanical and biological 

controls at current levels would be a result if the ―no action‖ alternative is 

chosen. 

a. Chemical Control 

The most common herbicide used for A. donax is glyphosate which may 

require continued application for 3 to 5 years for local control (Newhouser 

et al., 1999; Dudley, 2000). The herbicide imazypyr is also used for 

control along ditches and canals. However, chemical control methods are 

not feasible for large-scale infestations covering hundreds of river miles,

such as the infestation in the Bi-National Rio Grande Basin. Broadcast 

applications of herbicides could have adverse impacts on nontarget 

vegetation if not carefully applied. 

b. Mechanical Control

Mechanical methods of A. donax control include use of prescribed fire, 

heavy machinery (e.g. bulldozer, Hydro-axe,), hand-cutting, chipper, etc. 

Biomass removal may be necessary if there is a possibility that cut 

vegetation might create a flood hazard during high water events. Chipping 

2. Impact from 

Use of Other 

Control 

Methods 
14

is a costly method of removal. Equipment and labor are expensive relative 

to other forms of removal; however, the small dry chips that are produced 

pose little threat in terms of regeneration, and they do not form debris 

dams. Biomass removal by vehicle is expensive and generally not 

preferred due to its lack of cost-effectiveness. The use of heavy 

machinery, such as the Hydro-axe, is extremely expensive and slow, 

cutting only about 3 to 4 acres per day (Bell, 1997). Mechanical 

eradication with a backhoe has been ineffective because the rhizome 

fragments buried under the soil will readily re-sprout. Prescribed burning 

has not been successful because it cannot kill the rhizomes, and generally 

promotes A. donax regeneration over native riparian species. 

c. Biological Control

The Arundo wasp, Tetramesa romana Walker (Hymenoptera: 

Eurytomidae) was approved for release in April 2009. It currently occurs 

in Texas and California. It is not expected that Tetramesa romana

(T. romana) alone will completely control A. donax. However, the stem 

galling of A. donax caused by T. romana results in shortened internodes, 

stunted stems, and sometimes death of the stems.

These environmental consequences may occur even with the 

implementation of the biological control alternative, depending on the 

efficacy of R. donacis to reduce A. donax in the continental United States. 

B. Issue Permits for Environmental Release of 

R. donacis

Host specificity of R. donacis to A. donax has been demonstrated through 

scientific literature, field observations, and host-specificity testing. If an 

insect species only attacks one or a few closely related plant species, the

insect is considered to be very host-specific. Host specificity is an 

essential trait for a biological control organism proposed for 

environmental release.

a. Scientific Literature

Both the original description of R. donacis (as Targionia donacis, revised 

as Rhizaspidiotus donacis by Ferris (1943) and other collections from the 

native range (reviewed by Balachowsky, 1932; 1951) in France 

(Balachowsky, 1930; 1933; 1951), Spain (Balachowsky, 1935; GómezMenor Ortega, 1958; Martin-Mateo, 1983), Italy (Lupo, 1957), and North 

Africa (coastal Algeria) (Balachowsky, 1928) indicate that R. donacis has 

been collected only from A. donax, with the exception of one report from 

Turkey (Uygun et al., 1998) indicating a collection from common reed 

(Phragmites australis).

1. Impact of 

R. Donacis on 

Nontarget 

Plants
15

b. Field Collections and Observations 

Extensive surveys by Alan Kirk (USDA-ARS, European Biological 

Control Laboratory (EBCL), Montpelier, France) throughout the Western 

Mediterranean, including Morocco, confirmed the widespread presence of 

R. donacis on A. donax. Occasionally, this scale was found on Arundo 

plinii in Spain.

c. Host Specificity Testing

(1) Site of Quarantine and Field Studies

Host-specificity tests are tests of how many plant species R. donacis

attacks/eats. Field studies were conducted throughout Mediterranean 

Europe and in North America. Most studies were conducted near the 

ARS–European Biological Control Laboratory in Montpelier, France. 

R. donacis is native within 37 miles of the research grounds at the Campus 

Baillarguet Internacional. Laboratory studies were conducted at the 

USDA–APHIS Mission Biological Control Laboratory, Mission/Edinburg, 

Texas. 

(2) Test Plant List

(The list of plant species used for host-specificity testing of R. donacis is 

shown in appendix A.) 

A. donax belongs to the plant family Poaceae (grasses) and the subfamily 

Arundinoideae. Representatives of all of the subfamilies closely related 

to Arundinoideae (Chloridoideae, Centothecoidae, Panicoidae, and 

Micrairoideae) were included in the host range testing except for 

Micrairoideae which is not represented in North America. Representatives 

from more distant subfamilies within the Poaceae (Aristidoideae, 

Danthonioideae, Pooideae, and Bambusoideae) were also tested. 

Within the Arundinoideae are the following core genera: Arundo, 

Dregeochloa, Hakonechloa, Molinia, and Phragmites. Representatives 

from all of these genera were tested except Dregochloa, which is found 

only in southern Africa, and Hakonechloa, an uncommon exotic, 

ornamental species in North America. A plant in the genus Molinia was

obtained, but it is also a rarely used exotic ornamental. Of these genera, 

Phragmites is the most critical because it occurs with A. donax throughout 

a large part of its introduced range, and R. donacis has been reported on 

Phragmites australis in the literature. There are no native Arundo species 

in North or South America. The only other Arundo species present in 

North America is A. formosana. This plant is native to Taiwan and is an 

uncommon, exotic, ornamental in the San Francisco Bay Area. None of 
16

the other Mediterranean Arundo species (A. plinii, A. collina, or A. 

mediterranea) are present in North America.

To evaluate the genetic diversity of A. donax, the two dominant genotypes 

in the Rio Grande Basin (RGB) were collected from San Juan, Texas, in 

the Lower Rio Grande Valley and Laredo, Texas, 150 miles upriver. The 

Laredo genotype is the dominant genotype in the RGB above Laredo and,

therefore, is representative of the vast biomass of the invasive population. 

Considerable emphasis was placed on selection of Phragmites test plants. 

There is only one Phragmites species present in North America (P. 

australis), but there is a considerable body of knowledge associated with 

P. australis because of its worldwide distribution and invasiveness in 

northeastern North America (Tewksbury et al., 2002). Populations of 

P. australis from Rhode Island, California, and Texas were collected and 

used in testing. 

Within the Poaceae, the main agricultural grasses, including corn, wheat, 

sorghum, and rice were tested. Genetic material of these grasses was 

obtained from USDA–ARS Germplasm Repositories in Idaho, Georgia, 

and Colorado. Whole rice plants were obtained from the USDA–ARS 

laboratory in Beaumont, Texas.

Several habitat associates of A. donax were selected that represented 

plants that R. donacis could come into contact with in the western or gulf 

coast areas of North America. All of the habitat associates are native noneconomic species, except pecans, which are a native economic species.

Discussion of Host-Specificity Testing

In quarantine host-specificity testing, most plant species supported no 

R. donacis scales through any developmental stage. In no choice tests, 

there was low level survival and development of R. donacis on 

S. alterniflora and three Leptochloa species, less than 1 percent as 

compared to 43 percent development to the adult stage on A. donax. In 

additional testing of S. alterniflora no settling or development occurred on 

the plant, confirming that it is not expected to be a host of R. donacis. In 

field host range studies in Europe, R. donacis was not found on any other 

plant than A. donax.

Quarantine Host Range Tests (Goolsby, 2009). In no choice tests

(host-specificity tests where the target insect is offered only one test plant 

species and not offered the choice of either A. donax and the test plant 

species), 200 R. donacis crawlers were released on each test plant species. 

Crawlers that did not settle on plant tissues died within 2 to 3 days of 

release and, thus, were not expected to be observed at the time of plant 

dissection, 3 to 4 months after release of crawlers onto each plant. Early 
17

second-instar scales (sex not determinable) were uncommon on A. donax, 

A. formosana, and non-Arundo plants and did not vary in abundance 

between plant species (appendix B). Late second-instar females were also 

uncommon on A. donax (observed on 4 of 29 shoots), and did not differ in 

abundance between A. donax and the one non-Arundo plant on which they 

were observed, Cynodon dactylon (appendix B). 

Adult males (indicated by empty scale coverings) were significantly more 

abundant on A. donax than on any non-Arundo plant species, while not 

differing from A. formosana (appendix B). Adult males were 2.5-fold 

more abundant on A. donax (316 adult males found on 29 shoots) than on 

S. alterniflora (13 found on 3 shoots), and were 7 to 30-fold less abundant 

on 3 Leptochloa spp. than on A. donax (appendix B). Live adult females, 

representing the most long-lasting and damaging scale stage, were found 

on only one non-Arundo species, Leptochloa virgata, with three adults 

found on two shoots. Live adult female abundance per L. virgata plant 

was 41-fold lower than on A. donax, on which 599 adult females were 

found on 29 shoots (appendix B). Arundo donax was 6.9-fold higher than 

A. formosana in live adult female counts (appendix B). 

As an additional measure of development by females, counts of live and 

dead adult females were combined. Combined living and dead adult 

females were found on two Leptochloa species: L. fusca subsp. univervia

(three dead females on one of three plants tested) and L. virgata (four dead 

adult females, in addition to the three live females noted earlier, on one of 

the two plants tested). Dead adult females were also found on S.

alterniflora (total of 20 dead females found across two of three plants). 

These adults were originally reported as live because the grass leaf they 

were on died and it is not clear whether they would have survived. These 

values can be compared to A. donax, on which 669 live and dead adult 

females were found across 29 total plants. Average combined live and 

dead adult females per plant were 3.4-fold higher on A. donax than on 

S. alterniflora, 6.6-fold higher than on L. virgata, and 23-fold higher than 

on L. fusca subsp. uninervia (appendix B).

Total live scales were significantly higher on A. donax than any other 

plant species (appendix B). Forty of the 47 non-Arundo plant species did 

not support any R. donacis scales through any developmental stage. Total 

live scales were 3-fold more abundant on A. donax than on A. formosana, 

7.6-fold more abundant than on S. alterniflora, 11-fold more abundant 

than on Chasmanthium latifolium, 17 to 100-fold more abundant than on 

Leptochloa spp., 55-fold more abundant than on P. australis (exotic 

Rhode Island, USA genotype), and 100-fold more abundant than on 

Cynodon dactylon, all significant differences in mean comparisons. 

A followup no-choice test was performed involving A. donax from 

Laredo, Texas, and the four non-Arundo plant species on which small 
18

numbers of R. donacis males and/or females completed their immature 

development in prior host range tests. These species were further 

challenged by releasing 1,000 crawlers on each plant. The plants were 

dissected 3 months after crawler release. The results of the high rate tests 

are shown in appendix C. Survival and development of R. donacis on 

S. alterniflora and Leptochloa spp. was very low, less than 1 percent as 

compared to 43 percent development to the adult stage on A. donax. 

Mortality of crawlers under field conditions is likely to be much greater, 

thus further limiting the host range on R. donacis. 

In August 2010, additional quarantine choice and dispersal tests were 

conducted to ensure that S. alterniflora would not serve as a host for 

R. donacis. Rhizaspidiotus donacis crawlers were given the choice to 

disperse, settle, and develop on their host plant, A. donax, or the nontarget 

S. alterniflora. In these studies, no settling or development occurred on 

S. alterniflora. In another study, the ability of R. donacis crawlers to be 

wind dispersed from A. donax and then settle and develop on 

S. alterniflora was tested. Although it was found in this study that 

R. donacis crawlers can be dispersed by wind, they did not settle and 

develop on S. alterniflora. These studies confirm that S. alterniflora is not 

expected to be at risk from R. donacis.

Field Host Range Studies (Goolsby, 2009). In field survey of nontargets in Mediterranean Europe, hundreds of the nontarget plant species 

of concern were collected and dissected. No R. donacis or any other 

diaspidid scales were observed on any Leptochloa fusca subsp. uninervia

plants collected in Valencia, Seville, or Tortosa, Spain, whereas 

R. donacis was common on A. donax at the three sites. No R. donacis was 

observed on A. donax in the colder inland rice growing area of 

Merida/Badahoz where Leptochloa fasicularis was found.

No R. donacis were observed on Spartina versicolor at El Saler 

(Valencia). This site was the most intact natural area on the 

Mediterranean coast, and the two species have been growing together for 

many thousands of years. R. donacis was common on all the A. donax

stands in this natural area. In southeastern France, near Leucate, two 

populations of Spartina foliosa were collected and examined, one within 

500 m and the second 6 cm from A. donax. Chortinaspis subterranea

(Diaspidae) individuals were collected from 4 of 11 stems at the second 

site, and heavy populations of R. donacis were observed on adjacent 

A. donax. No R. donacis were observed on S. foliosa.

In addition, other grasses growing with A. donax, identified as Agropyrum, 

Cynodon, Elymus, Thinopyrum, Panicum, and Chloris, were sampled at 

the above locations in Spain. Ten to 30 of each species within 0.5 m of 

R. donacis populations were collected, dissected, and evaluated. No 

R. donacis individuals were found on the above grass species. 
19

In a field host exposure test, 20 Leptochloa dubia plants were returned to 

quarantine facilities for dissection and inspection after 6 months in the 

field. Plants were green and in good shape. Individual leaf blades and 

stems were separated and inspected for any evidence of R. donacis. No 

R. donacis individuals of any life stage were detected. This indicates that 

despite repeated exposure to multiple cohorts of crawlers emanating from 

the adjacent A. donax, L. dubia was not a field host for the scale (Goolsby, 

2009).

R. donacis is one of the most damaging insects to A. donax in its native 

range. The scale attacks the rhizome and developing underground buds by 

feeding on plants cells that carry out photosynthesis and cellular 

respiration and can store food for the plant. Damage symptoms include 

side shoot distortion with thin, brittle, short canes. Crawler feeding often 

causes distortion and a witch’s broom effect (an abnormal brushlike 

growth of weak, closely clustered shoots). Other effects over time include 

gradual thinning, leaf reduction, and a sickly, yellowish-clouded 

appearance of canes. The overall effect is diminished vigor with A. donax

stands characterized by thin, brittle, naked canes. 

Assessment of impact on A. donax by the previously released T. romana

combined with R. donacis was conducted in a quarantine greenhouse 

study (Goolsby, 2009). T. romana alone and T. romana plus R. donacis

caused significant damage to A. donax by suppressing leaf and stem 

elongation and by stimulating the production of side branches during a 

12-week period. The R. donacis plus T. romana treatment produced only 

slightly greater plant impacts as compared to T. romana alone, most likely 

because of the longer developmental time of R. donacis. The impact of 

R. donacis from the crawler to late second instar is not as great as the 

effect caused by the larger adult female. A longer study that fully 

encompassed the entire 6-month development period of R. donacis may 

have shown more impact by R. donacis combined with T. romana. No 

negative interactions were observed between the two biological control 

agents during the 12-week study. Continued observation of the test plants 

revealed that damage by R. donacis was significant 4 to 6 months after 

release. Large colonies of the scale formed at the base of the rhizome, 

which appeared to further suppress any regrowth, even 8 to 10 months 

after release. These results are consistent with field observations in 

Europe. In Europe, R. donacis causes long-term debilitation of A. donax 

stands.

Once a biological control agent, such as R. donacis, is released into the 

environment and becomes established, there is a slight possibility that it

could move from the target plant (A. donax) to attack nontarget plants. 

Host shifts by introduced weed biological control agents to unrelated 

plants are rare (Pemberton, 2000). Native species that are closely related 

to the target species are the most likely to be attacked (Louda et al., 2003). 

3. Uncertainties 

Regarding the 

Environmental 

Release of 

R. donacis

2. Impact of 

R. donacis on 

A. donax
20

If other plant species were to be attacked by R. donacis, the resulting 

effects could be environmental impacts that may not be easily reversed. 

Biological control agents, such as R. donacis, generally spread without 

intervention by man. In principle, therefore, release of this biological 

control agent at even one site must be considered equivalent to release 

over the entire area in which potential hosts occur and in which the 

climate is suitable for reproduction and survival.

In addition, this agent may not be successful in reducing A. donax

populations in the continental United States. Worldwide, biological weed 

control programs have had an overall success rate of 33 percent; success 

rates have been considerably higher for programs in individual countries 

(Culliney, 2005). Actual impacts on A. donax by R. donacis will not be 

known until after release occurs and post-release monitoring has been 

conducted. It is expected that R. donacis will work together with the 

previously released biological control agent, T. romana, to reduce 

populations of A. donax.

―Cumulative impacts are defined as the impact on the environment which 

results from the incremental impact of the action when added to other past, 

present and reasonably foreseeable future actions regardless of what 

agencies or person undertakes such other actions‖ (40 CFR 1508.7).

Many Federal and State agencies, as well as private entities, conduct 

programs to manage A. donax, as well as other invasive weeds. Chemical 

and mechanical methods, as described previously in this document, are 

used in a wide range of habitats. Some of these control programs are 

listed below. 

Dept. of Homeland Security, Customs and Border Protection: The Border 

Patrol is planning to use mechanical and chemical methods to control 

A. donax along the United States and Mexican border in Webb County, 

Texas, to assist in law enforcement activities associated with illegal border 

crossings (DHS, 2008).

Dept. of State, International Boundary and Water Commission (IBWC), El 

Paso, Texas: The IBWC use annual mowing along the sections of the Rio 

Grande to manage access to the River.

U.S. Fish and Wildlife Service, International Services: Chemical control 

is used to stop the spread of A. donax at the Cuatro Cienegas nature 

preserve in Coahuila, Mexico

U.S. Dept. of Interior, National Park Service, Big Bend National Park, 

Texas: Park staff use a combination of fire and herbicides to manage 

A. donax.

4. Cumulative 

Impacts
21

Texas Dept. of Parks and Wildlife, Bentsen State Park, Mission, Texas: 

Park staff use herbicides to control A. donax and Phragmites growing in 

the alternate river channels.

Lower Rio Grande Valley Irrigation and Drainage Districts, Brownsville, 

Harlingen, Mercedes, McAllen, and La Hoya, Texas: All of the irrigation 

districts report that they use mechanical control, shredders, and backhoes 

for control of A. donax along irrigation canals and drainage ditches.

Maverick Irrigation District, Eagle Pass, Texas: The district reports the 

use of mechanical and chemical control to manage A. donax along 

irrigation canals and drainage ditches.

Texas Dept. of Transportation (TXDot), Austin, Texas: The State 

vegetation coordinator reports that TXDot uses mechanical and chemical 

control to maintain populations of A. donax growing along roadsides. The 

problem is most severe in south-central Texas near College Station.

Team Arundo Del Norte, California: A consortium of homeowner 

associations, municipalities, and the State of California combine their 

resources to use chemical control, mechanical removal, and revegetation 

to restore ecologically sensitive rivers and creeks in northern California.

Team Arundo Del Sur, California: A consortium of homeowner 

associations, municipalities, and the State of California combine their 

resources to use chemical control, mechanical removal and revegetation to 

restore ecologically sensitive rivers and creeks in southern California.

California Dept. of Transportation (CalDOT), Sacramento, California: 

CalDOT uses mechanical and chemical control to manage A. donax along 

highways and bridges in the State.

Private landowners throughout the southern tier of the United States use a 

variety of methods to control A. donax where it has become invasive on 

private land.

Santa Ana Watershed Association (SAWA), California: SAWA has 

removed over 2,000 acres of A. donax from the Santa Ana watershed to 

restore habitat for native species, including the southwestern willow 

flycatcher.

USDA, Agriculture Research Service is conducting releases of the 

previously released biological control agent T. romana in the vicinity of 

Laredo, Texas.

Release of R. donacis is not expected to have any negative cumulative 

impacts in the continental United States because of its host specificity to 
22

A. donax. Effective biological control of A. donax will have beneficial 

effects for weed management programs, and may result in a long-term, 

non-damaging method to assist in the control of A. donax, and prevent its 

spread into other areas potentially at risk from invasion.

Section 7 of the Endangered Species Act (ESA) and ESA’s implementing 

regulations require Federal agencies to ensure that their actions are not 

likely to jeopardize the continued existence of federally listed threatened 

and endangered species or result in the destruction or adverse modification 

of critical habitat. 

A. donax has been documented to be the cause of the extinction of 

endemic fish species in the Rio Nadadores in Coahuila, Mexico, near 

Cuatro Cienegas (McGaugh et al., 2006). This region is rich in 

biodiversity, including fresh water stromatolites. The U.S. Fish and 

Wildlife Service, Pronatura Noreste, and the University of Texas at Austin 

are trying to eradicate A. donax from the most sensitive areas of Cuatro 

Ciénegas Natural Area. In California, least Bells’ vireo (Vireo bellii 

pusillus Coues) is threatened by A. donax invasion (Boose and Holt, 

1999). On the Rio Grande, Correl’s false dragon head, Physostegia 

correllii, is a rare species which is severely impacted by A. donax.

a. Plants 

There are 13 federally listed species in the plant family Poaceae in the 

continental United States. APHIS has determined that environmental 

release of R. donacis will have no effect on Alopecurus aequalis var. 

sonomensis (Sonoma alopecurus), Poa atropurpurea (San Bernardino 

bluegrass) and its designated critical habitat, Poa napensis (Napa 

bluegrass), or Zizania texana (Texas wild-rice) and its designated critical 

habitat. These species occur in either the subfamily Pooidae or 

Ehrhartordeae, both distantly related subfamilies to Arundinoideae. Some 

species belonging to the subfamily Pooideae were tested (Elymus 

virginicus, Sporobolus wrightii, and Triticum aestivum) but no 

development occurred on these plants. Alopecurus pratensis L. (meadow 

foxtail) is currently being tested against R. donacis as a surrogate for 

Alopecurus aequalis var. sonomensis. Preliminary results have indicated 

that no crawlers have settled on the plant (100 percent mortality of 

crawlers (J. Goolsby, pers. comm.).

The remaining listed grass species occur in the subfamily Chlordoideae. 

In host specificity testing, there was some minor development on some 

species belonging to this subfamily (Cynodon dactylon, Leptochloa spp., 

and S. alterniflora). Species of Leptochloa and Spartina exist in the native 

range of the scale and were surveyed and challenged in a host exposure 

test. Neither these species nor other species of Chlorodoideae are hosts 

for R. donacis in Europe. R. donacis would be unable to survive on 

5. Endangered 

Species Act
23

Neostapfia colusana (Colusa grass), Orcuttia californica (California 

Orcutt grass), Orcuttia inaequalis (San Joaquin Orcutt grass), Orcuttia 

pilosa (hairy Orcutt grass), Orcuttia tenuis (slender Orcutt grass), Orcuttia 

viscida (Sacramento Orcutt grass), Tuctoria greenei (Greene’s tuctoria), or 

Tuctoria mucronata (Solano grass) because part of their life cycle occurs 

in vernal pools. Orcuttia plants grow underwater for 3 months or more 

and have evolved specific adaptations for aquatic growth (Keeley, 1998). 

Neostapfia colusana occurs in large or deep vernal pools with substrates 

of high mud content. Tuctoria greenei is known only from vernal pools in 

the Central Valley of California. Tuctoria mucronata is an annual grass 

that germinates in temporary pools, producing slender leaves that float on 

the water's surface, and then, when the pools dry out for the summer, 

producing shoots and flowers (the inflorescence is 1.5 to 6 cm long) 

(NatureServe, 2009). Finally, all of the above listed vernal pool grasses 

are annual grasses. R. donacis is a terrestrial scale insect that feeds on 

rhizomes and stem node tissue of long-lived, perennial Arundo spp. 

Rhizaspidiotus donacis has a 6 month or longer life cycle. The life cycle 

of those vernal pool grasses would be too short to support the development 

of R. donacis. Therefore, APHIS has determined that the release of 

R. donacis may affect, but is not likely to adversely affect N. colusana, 

O. californica, O. inaequalis, O. pilosa, O. tenuis, O. viscida, T. greenei, 

or T. mucronata.

Swallenia alexandrae (Eureka dunegrass), a perennial plant in the 

subfamily Chlordoideae, grows in an environment that is hostile to both 

Arundo donax and R. donacis. It is located in four dunes in the Eureka 

Valley, Inyo County, California. All four populations are on lands 

managed by Death Valley National Park. Death Valley is the hottest and 

driest place in North America. Summer temperatures often top 120 °F 

(49 °C). Average rainfall is less than 2 inches (5 cm). The high summer 

temperatures would be lethal to R. donacis, which is a Mediterranean 

insect (J. Goolsby, pers. comm.). The Eureka dunes also experience 

winter freezes. The distribution of R. donacis in Europe is limited to only 

the climates warm enough for citrus to be grown. Therefore, both the high 

and low temperature extremes would be unsuitable for establishment of 

R. donacis (J. Goolsby, pers. comm.). Therefore, APHIS has determined 

that release of R. donacis may affect, but is not likely to adversely affect 

S. alexandrae.

b. Animals

A. donax has been found to be used by some wildlife, although it provides 

little value for native wildlife in comparison to native vegetation, 

especially when it forms large, monotypic stands. Two endangered bird 

species, least Bell’s vireo (Vireo bellii pusillus) and the southwestern 

willow flycatcher (Empidonax traillii extimus), have been found to use 

A. donax as a nest host (Pike et al., 2002; Kus, 2000). However, the 
24

recovery plan for the southwestern willow flycatcher indicates that this 

bird rarely nests in A. donax, and also indicates that in California, A. 

donax is spreading rapidly, forming dense, monotypic stands unsuitable 

for flycatchers (FWS, 2002). Least Bell’s vireos have been found nesting

on A. donax along the Santa Clara River and the San Luis Rey River. In 

the U.S. Fish and Wildlife Service’s 5-year review of the least Bell’s vireo 

(FWS, 2006), habitat loss and invasion of riparian habitat by introduced 

exotic plant species (primarily A. donax) is listing factor 1 for the species. 

R. donacis is not expected to cause rapid, drastic reduction of A. donax, 

but could potentially decrease the reproductive capacity of A. donax. 

Thus, A. donax would not be rapidly removed from the environment, 

leaving nesting habitat for these species. Therefore, release of R. donacis

may affect, but is not likely to adversely affect, nesting by the least Bell’s 

vireo or the southwestern willow flycatcher, and may potentially benefit 

their designated critical habitat as A. donax does not provide suitable 

habitat for these birds. 

In Texas, A. donax provides migratory habitat for the Gulf Coast 

jaguarundi (Herpailurus (=Felis) yagouaroundi cacomitli) and ocelot 

(Leopardus (=Felis) pardalis). However, R. donacis is not expected to 

cause rapid, drastic reduction of A. donax, but could potentially diminish 

the vigor of A. donax, resulting in stands which are characterized by thin 

brittle naked canes. Thus, A. donax would not be rapidly removed from 

the environment, leaving migratory cover for these species. Therefore, 

release of R. donacis may affect, but is not likely to adversely affect the 

gulf coast jaguarundi or ocelot.

S. alterniflora is an important component of the wintering habitat of the 

whooping crane (Grus americana). In additional host specificity testing 

conducted in August 2010, R. donacis did not develop on S. alterniflora. 

Therefore, APHIS has determined that release of R. donacis may affect, 

but is not likely to adversely affect the whooping crane or its critical 

habitat.

APHIS submitted a biological assessment to the U.S. Fish and Wildlife 

Service (Service) in June 2009 and again in January 2010, requesting 

Service concurrence. Numerous email and telephone communications 

have occurred between APHIS and the Service to clarify aspects of the 

release of R. donacis. In a letter dated September 13, 2010, the Service 

concurred with APHIS’s determinations that release of R. donacis may 

affect, but is not likely to adversely affect, the plants N. colusana, O. 

californica, O. inaequalis, O. pilosa, O. tenuis, O. viscida, T. greenei, T. 

mucronata, and S. alexandrae, or the animals V. bellii pusillus, E. traillii 

extimus, L. pardalis, H. yagouaroundi cacmitli, and G. americana or their 

designated critical habitats.
25

V. Other Issues

Consistent with Executive Order (EO) 12898, ―Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations,‖ APHIS considered the potential for disproportionately high 

and adverse human health or environmental effects on any minority 

populations and low-income populations. There are no adverse 

environmental or human health effects from the field release of 

R. donacis, and the release will not have disproportionate adverse effects 

to any minority or low-income populations. 

Consistent with EO 13045, ―Protection of Children From Environmental 

Health Risks and Safety Risks,‖ APHIS considered the potential for 

disproportionately high and adverse environmental health and safety risks 

to children. No circumstances that would trigger the need for special 

environmental reviews are involved in implementing the preferred 

alternative. Therefore, it is expected that no disproportionate effects on 

children are anticipated as a consequence of the field release of R. donacis.

EO 13175, ―Consultation and Coordination with Indian Tribal 

Governments,‖ was issued to ensure that there would be ―meaningful 

consultation and collaboration with tribal officials in the development of 

Federal policies that have tribal implications....‖

APHIS is consulting and collaborating with Indian tribal officials to 

ensure that they are well-informed and represented in policy and program 

decisions that may impact their agricultural interests in accordance with 

EO 13175, ―Consultation and Coordination with Indian Tribal 

Governments.‖
26

VI. Agencies, Organizations, and Persons 

Consulted

The Technical Advisory Group for the Biological Control Agents of 

Weeds (TAG) recommended the release of R. donacis on July 6, 2009. 

TAG members that reviewed the release petition (Goolsby, 2009) included 

representatives from the Bureau of Indian Affairs, APHIS, Cooperative 

State Research, Education, and Extension Service, Forest Service, U.S. 

Geological Survey, Environmental Protection Agency, U.S. Army Corps 

of Engineers, Bureau of Land Management, Bureau of Reclamation, the 

National Plant Board, and representatives from Canada and Mexico. 

This EA was prepared and reviewed by APHIS. The addresses of 

participating APHIS units, cooperators, and consultants (as applicable) 

follow.

U.S. Department of Agriculture

Animal and Plant Health Inspection Service

Policy and Program Development 

Environmental Services

4700 River Road, Unit 149

Riverdale, MD 20737

U.S. Department of Agriculture

Animal and Plant Health Inspection Service

Plant Protection and Quarantine 

Pest Permitting

4700 River Road, Unit 133

Riverdale, MD 20737

U.S. Department of Agriculture

Kika de la Garza Subtropical Agricultural Research Center

Beneficial Insects Research Unit

2413 E. Hwy. 83

Weslaco, TX 78596
27

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Appendix A. Host Plant Test List for R. donacis (Goolsby, 2009)

Order Family Sub-family Scientific Name

Common 

Name

Indigenous 

to U.S.

Indigenous 

to Mexico

Grain/ 

Forage Ornamental Habitat Associate

Cyperales Poaceae Arundinoideae Arundo donax L. Laredo, TX giant reed No No No Yes -

― ― ―

Arundo donax L. San Juan, 

TX giant reed No No No Yes -

― ― ― A. formosana Hack. fountain reed No No No Yes No

― ― ―

Phragmites australis (Cav.) 

Trin. ex Steud. Rhode Island 

(exotic European ecotype)

common 

reed No No No No No

― ― ―

Phragmites australis (Cav.) 

Trin. ex Steud. 

Mercedes, TX

common 

reed Yes Yes No No Yes

― ― ―

Phragmites australis (Cav.) 

Trin. ex Steud. 

San Benito, TX

common 

reed Yes Yes No No Yes

― ― ―

Phragmites australis (Cav.) 

Trin. ex Steud. Colorado 

River, CA

common 

reed Yes Yes No No Yes

― ― ― Molinia caerulea (L.) Moench Moore grass No No No Yes No

― ― Aristidoideae Aristida purpurea Nutt. var. 

longiseta (Steud.) Vasey

red three 

awn 

Yes Yes No No No

― ― Centothecoideae Chasmanthium latifolium 

(Michx.) Yates

inland sea 

oats Yes Yes No Yes Yes

― ― Chloridoideae Bouteloua hirsuta Lag. hairy grama Yes Yes Yes No No

― ― ― Cynodon dactylon (L.) Pers. Bermuda 

grass

No No Yes Yes Yes

― ― ―

Dichanthelium acuminatum 

(Sw.) Gould and Clark

tapered 

rosette grass Yes Yes Yes No No

― ― ― Eragrostis intermedia Hitchc. plains 

lovegrass Yes Yes Yes No No

― ― ―

Eragrostis spectablilis (Pursh) 

Steud.

purple 

lovegrass Yes Yes Yes Yes No

― ― ―

Leptochloa dubia (Kunth) 

Nees

green 

sprangletop

Yes Yes Yes No No
―

――

Leptochloa fusca (L.) Kunth 

subsp. uninervia (J. Presl) N. 

Snow

Mexican 

sprangletop Yes Yes No No No

―――

Leptochloa panicea (A. 

Retzius) J. Ohwi subsp. Brachiata

red 

sprangletop Yes Yes No No No

―――

Leptochloa virgata (L.) P. 

Beauv. 

tropic 

sprangletop Yes Yes No No No

―――

Muhlenbergia capillaris 

(Lam.) Trim.

hairawn 

muhly Yes Yes Yes Yes No

――― Spartina alterniflora Loisel. smooth 

cordgrass Yes No? No No Yes

―――

Spartina spartinae (Trin.) 

Merr. ex Hitchc.

Gulf 

cordgrass Yes Yes No No Yes

―――

Tridens albescens (Vasey) 

Wooton & Standl. white Tridens Yes Yes Yes No Yes

――― Uniola paniculata L. sea oats Yes Yes No No Yes

―― Danthonioideae Cortaderia selloana (Schult. & 

Schult. f.) Asch. & Graebn.

pampas 

grass

No No No Yes No

―――

Danthonia spicata (L.) P. 

Beauv. ex Roem. & Schult.

poverty 

oatgrass Yes Yes Yes No No

―― Panicoideae Andropogon glomeratus 

(Walter) Britton et al.

bushy 

bluestem Yes Yes Yes Yes Yes

―――

Digitaria cognata (Schult.) 

Pilg.

fall 

witchgrass Yes Yes Yes No No

――― Panicum amarum Elliot. bitter 

panicgrass Yes Yes Yes No No

――― Panicum hirsutum Sw. hairy 

panicum Yes Yes No No Yes

――― Panicum virgatum L. switchgrass Yes Yes Yes Yes No

――― Pennisetum ciliare (L.) Linkbuffelgrass No No Yes No Yes

――― Saccharum officinarum L. sugarcane No No Yes No No

―――

Schizachyrium scoparium 

(Michx.) Nash

little 

bluestem Yes Yes Yes Yes Yes
― ― ― Sorghum bicolor (L.) Moench sorghum No No Yes No No

― ― ― Tripsacum dactyloides (L.) L. eastern 

gamagrass 

Yes Yes Yes No Yes

― ― ― Zea mays L. corn No No Yes No No

― ― Pooideae Elymus virginicus L. Virginia 

wildrye Yes No Yes No Yes

― ― ―

Sporobolus wrightii Munro ex 

Scribn.

alkalai 

sacaton Yes Yes Yes No Yes

― ― ― Triticum aestivum L. wheat No No Yes No No

― ― Bambusoideae Arundinaria gigantea (Walter) 

Muhl. giant cane Yes No No Yes Yes

― ― ― Oryza sativa L. rice No No Yes No No

― Cyperaceae ---- Cyperus articulatus L. jointed 

flatsedge Yes Yes No No Yes

― ― ----

Schoenoplectus maritimus 

(L.) Lye alkali bulrush Yes? Yes? No No Yes

Eriocaules Eriocaulaceae ---- Eriocaulon decangulare L. tenangle 

pipewort Yes Yes No No No

Typhales Typhaceae ---- Typha domingensis Pers. narrowleaf 

cattail Yes Yes No No Yes

Arecales Arecaceae ---- Sabal mexicana Mart. Rio Grande 

palmetto Yes Yes No Yes Yes

Juglandales Juglandaceae ----

Carya illinoinensis 

(Wangenh.) K. Koch pecan Yes Yes Yes Yes Yes

Salicales Salicaceae ---- Salix exigua Nutt. narrowleaf 

willow Yes Yes No No Yes

Asterales Asteraceae ---- Baccharis neglecta Britton dryland 

Baccharis Yes Yes No No Yes

― Oleaceae ---- Fraxinus berlandieriana DC. Rio Grande 

ash Yes Yes No Yes Yes
Appendix B. Results of No-Choice Host Range Tests for Rhizaspidiotus donacis (Goolsby, 2009). 

(Values are mean numbers of scale insects per plant.*)

Test Plant 

Species Reps

Live 

Whitecaps/ 

Early 2nd 

Instar

Live Late 

2nd Instar

Adult 

Male** 

Live Adult 

Female

Live+Dead 

Adult Female

Total Live 

All Stages

mean ±SE mean ±SE mean ±SE mean ±SE mean ±SE mean ±SE

Arundo donax 

Laredo, TX 13 2.30±1.99 0.85±0.48 9.62±2.83 24.15±7.10 27.23±7.66 37.15±10.71

Arundo donax 

San Juan TX 16 0.38±0.38 0 11.94±2.34 17.81±4.56 19.69±4.60 30.13±5.60

Arundo donax 

pooled Laredo and 

San Juan, TX

29 1.24±0.92a0.38±0.22a10.90±1.79a20.66±4.02a23.07±4.24a33.28±5.63a

Arundo formosana 3 0 0 7.33±3.67a

3.00±1.53b5.00±2.89b11.00±5.57b

Phragmites 

australis 

Charlestown RI

(Exotic European 

ecotype)

5 0.40±0.4a0 0.20±0.20b0 0 0.60±0.60b

Phragmites 

australis 

Mercedes, TX

4 0 0 0 0 0 0

Phragmites 

australis 

San Benito, TX

3 0 0 0 0 0 0

Phragmites 

australis 

Colorado River CA

6 0 0 0 0 0 0

Molinia caerulea 3 0 0 0 0 0 0

Aristida purpurea 

var. longiseta 3 0 0 0 0 0 0

Chasmanthium 

latifolium 2 0.50±0.50a

0 0 0 0 0.50±0.50b

Bouteloua hirsuta 3 0 0 0 0 0 0

Cynodon dactylon 3 0 0.33±0.33a

0 0 0 0.33±0.33b

Dichanthelium 

acuminatum 3 0 0 0 0 0 0

Eragrostis 

intermedia 3 0 0 0 0 0 0

Eragrostis 

spectablilis 3 0 0 0 0 0 0

Leptochloa fusca

subsp. uninervia

3 0.33±0.33a0 1.00±1.00b0 1.00±1.00b1.33±1.33b

Leptochloa 

panicea subsp. 

Brachiata

3 0 0 0.33±0.33b0 0 0.33±0.33b

Leptochloa virgata 2 0 0 0.50±0.50b

1.50±1.50b3.50±3.50b2.00±2.00b
Muhlenbergia

Capillaris

3 0 0 0 0 0 0

Spartina alterniflora 3 0 0 4.33±4.33b

0 6.67±6.17b4.33±4.33b

Spartina spartinae 3 0 0 0 0 0 0

Tridens albescens 3 0 0 0 0 0 0

Uniola paniculata 3 0 0 0 0 0 0

Cortaderia selloana 5 0 0 0 0 0 0

Danthonia spicata 1 0 0 0 0 0 0

Andropogon 

glomeratus

3 0 0 0 0 0 0

Digitaria cognata 3 0 0 0 0 0 0

Panicum amarum 3 0 0 0 0 0 0

Panicum hirsutum 3 0 0 0 0 0 0

Panicum virgatum 3 0 0 0 0 0 0

Pennisetum ciliare 3 0 0 0 0 0 0

Saccharum 

officinarum

3 0 0 0 0 0 0

Schizachyrium 

scoparium

3 0 0 0 0 0 0

Sorghum bicolor 3 0 0 0 0 0 0

Tripsacum 

dactyloides

3 0 0 0 0 0 0

Zea mays 3 0 0 0 0 0 0

Elymus virginicus 1 0 0 0 0 0 0

Sporobolus wrightii 3 0 0 0 0 0 0

Triticum aestivum 3 0 0 0 0 0 0

Arundinaria 

gigantea

3 0 0 0 0 0 0

Oryza sativa 3 0 0 0 0 0 0

Cyperus articulatus 3 0 0 0 0 0 0

Schoenoplectus 

maritimus

3 0 0 0 0 0 0

Eriocaulon 

decangulare

3 0 0 0 0 0 0

Typha domingensis 4 0 0 0 0 0 0

Sabal mexicana 3 0 0 0 0 0 0

Carya illinoinensis 3 0 0 0 0 0 0

Salix exigua 3 0 0 0 0 0 0

Baccharis neglecta 3 0 0 0 0 0 0

Fraxinus 

berlandieriana

3 0 0 0 0 0 0

* Two hundred crawlers placed on each plant. Means within the same column with the same letter are not significantly different in 

least-square comparisons of means to pooled A. donax from Laredo and San Juan, TX (in bold above) (P > 0.05).

** Completion of male development to the winged adult stage is inferred from empty 2nd instar scale cover.
Appendix C. Results of No-Choice Host Range Tests for Rhizaspidiotus donacis in which 1,000 

Crawlers Were Released Per Plant (Goolsby, 2009). (Values are mean numbers of 

scale insects per plant.*)

Test Plant 

Species Reps

Live 

Whitecaps/ 

Early 2nd 

Instar

Live Late 

2nd Instar

Adult 

Male** 

Live Adult 

female

Live+Dead 

Adult 

Female

Total Live 

All Stages

mean ±SE mean ±SE mean ±SE mean ±SE mean ±SE mean ±SE

Arundo donax 

Laredo, TX 2 12.5±8.5a

6.00±0.00 249±24.0a129±40.0a177±53a398±25.5a

Leptochloa

fusca subsp. 

uninervia

3 0 0 1.00±1.00b0 0.67±0.67b1.00±1.00b

Leptochloa 

panicea subsp. 

brachiata

3 0.33±0.33b0 1.67±1.67b0 7.00±7.00b2.00±1.53b

Leptochloa 

virgata 2 0 0 1.50±1.50b

5.00±5.00b6.50±6.50b6.50±6.50b

Spartina 

alterniflora 3 0 0 0 0.33±0.33b

1.67±0.33b0.33±0.33b