United States 

Department of 

Agriculture

Marketing and 

Regulatory 

Programs

Animal and 

Plant Health 

Inspection 

Service

Field Release of 

Megamelus scutellaris,

Berg (Hemiptera: 

Delphacidae), for 

Biological Control of 

Water Hyacinth Eichhornia 

crassipes Mart. (Solms) 

(Pontederiales: 

Pontederiaceae) in the 

Continental United States

Environmental Assessment,

January 2010
Field Release of Megamelus 

scutellaris, Berg (Hemiptera: 

Delphacidae), for Biological Control 

of Water Hyacinth Eichhornia 

crassipes Mart. (Solms) 

(Pontederiales: Pontederiaceae) in 

the Continental United States

Environmental Assessment, 

January 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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recommendation or endorsement by the U.S. Department of Agriculture 

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This publication reports research involving pesticides. All uses of pesticides

must be registered by appropriate State and/or Federal agencies before they 

can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals, 

desirable plants, and fish or other wildlife–if they are not handled or applied 

properly. Use all pesticides selectively and carefully. Follow recommended 

practices for the disposal of surplus pesticides and pesticide containers.
Table of Contents

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

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

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

IV. Environmental Consequences............................................. 8

V. Other Issues ........................................................................ 17

 

VI. Agencies, Organizations, and Individuals Consulted...... 18

 

VII. References........................................................................... 19

Table 1. Worldwide Distribution of Species of 

 Pontederiaceae............................................................... 7

Table 2. Species of Pontederiaceae in the United States ......... 8

Table 3. Seven Categories of Plants Considered for the 

Test Plant List............................................................... 11

VIII. Appendix A

Appendix B

Appendix C

Appendix D

Appendix E
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)

Permit Unit is proposing to issue permits for release of the insect

Megamelus scutellaris Berg (Hemiptera: Delphacidae). The agent would 

be used by the applicant for biological control of water hyacinth, 

Eichhornia crassipes Mart. (Solms) (Pontederiales: Pontederiaceae), in the 

continental United States. Before permits are issued for release of M. 

scutellaris, the APHIS–PPQ Permit Unit needs to 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 of 1969 (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 M. 

scutellaris to control infestations of water hyacinth within the continental 

United States. This EA considers a ―no action‖ alternative and the 

potential effects of the proposed action.

The applicant’s purpose for releasing M. scutellaris is to reduce the 

severity of infestations of water hyacinth in the United States. Water 

hyacinth originated in lowland tropical South America, probably in the 

Amazon Basin (Barrett and Forno, 1982). Water hyacinth is a floating 

plant. Its erect, free-floating habit and showy flowers made it attractive 

for use in ornamental ponds and garden pools which inevitably led to 

spread of the plant by humans. It was first introduced into the United 

States in the late 1800s, and then into many tropical and subtropical (and 

some warm-temperate) regions of the world (Gopal, 1987). The growth 

form is sympodial2and individual rosettes reproduce to form extensive 

floating mats which, in mature stands, extend a meter or more above the 

water surface (Center and Spencer, 1981). Problems caused by water 

hyacinth in areas where it is has invaded are well documented (Center,

1994), and result from its rapid growth, ability to re-infest via seeds or 

from plant fragments, and lack of natural enemies. Infestations negatively 

affect water traffic, water quality, infrastructure for pumping and 

hydroelectric operations, water use, and biodiversity (Schmitz et al.,

1993). Other problems include property damage during floods, water loss 

 

1

Regulations implementing the National Environmental Policy Act of 1969 (42 

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

A plant whose main stem grows horizontally and that has lateral branches that stop growing at a 

certain point.
2

due to evapotranspiration, and increases in mosquito populations. Water 

hyacinth remains one of the world's most troublesome aquatic weed as it 

continues to invade water bodies and wetlands in new regions (Julien et 

al., 1996). 

Existing water hyacinth management options (discussed below) are 

ineffective, expensive, temporary, or have non-target impacts. In addition, 

herbicide programs periodically disrupt the life cycles of the currently 

released insects used for biological control of water hyacinth, thus, 

limiting their potential. As a result, more mobile agents with higher 

reproductive capacities are needed that can survive disruptions of water 

hyacinth communities by herbicide applications. For these reasons, the

applicant has a need to identify an effective, host-specific biological 

control organism and release it into the environment for the control of 

water hyacinth. 

II. Alternatives

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

Permit Unit—no action and issuance of permits for environmental release 

of M. scutellaris. Although APHIS’ alternatives are limited to a decision 

of whether to issue permits for release of M. scutellaris, other methods 

available for control of water hyacinth are also described. These control 

methods are not decisions to be made by APHIS, and are likely to 

continue whether or not permits are issued for environmental release of M.

scutellaris. These are methods presently being used to control water 

hyacinth by public and private concerns. 

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

Under this third alternative, the APHIS–PPQ Permit Unit would have 

issued permits for the field release of M. scutellaris, however, the permits 

would contain special provisions or requirements concerning release 

procedures or mitigating measures, such as limited release of M. 

scutellaris. No issues have been raised which would indicate that special 

provisions or requirements are necessary.

A. No Action 

Under the no action alternative, the APHIS–PPQ Permit Unit would not 

issue permits for the field release of M. scutellaris for the control of water 

hyacinth—the release of this biological control agent would not take 

place. The following methods are presently being used to control water 

hyacinth; these methods will continue under the ―no action‖ alternative 

and are likely to continue even if permits are issued for release of M.

scutellaris.
3

Treatment with the isooctyl esters and dimethylamine salts of 

2,4-dichlorophenoxy acetic acid (2,4-D) is the principle chemical control 

alternative employed in the United States, although diquat and glyphosate 

are also used (Vandiver et al., 1999). The costs depend on the size of the 

treatment area, the scale of the treatment, and the herbicide dosage. 

Current costs per acre range from $250 for glyphosate to $300 to $1,000 

for 2,4-D (Gibbons et al., 1999). 

This method is better suited to small isolated drainages but all plant 

fragments must be removed to avoid re-sprouting. Equipment includes 

rakes, mechanical harvesters, and suction dredgers. Excluding volunteer 

labor for smaller sites, harvesting costs can range from $500 to $800 per 

acre with additional costs for mobilization and equipment ($35,000 to 

$111,000) (WSDE, 2001). There may be additional fees for disposal of 

plant material. 

Three insects were released in the United States during the 1970s—

Neochetina eichhorniae Warner (Coleoptera: Curculionidae) beginning in 

1972, N. bruchi Hustache (Coleoptera: Curculionidae) beginning in 1974, 

and Niphograpta (=Sameodes) albigutallis (Warren) (Lepidoptera: 

Pyralidae) beginning in 1977. These insects now occur throughout the 

range of water hyacinth in the United States (Center et al., 1999b). 

B. Issue Permits for Environmental Release of 

M. scutellaris

Under this alternative, the APHIS–PPQ Permit Unit would issue permits

for the field release of M. scutellaris for the control of water hyacinth

wherever it occurs in the continental United States. These permits would 

contain no special provisions or requirements concerning release 

procedures or mitigating measures.

Biological Control Agent Information

Insect Taxonomy

Order: Hemiptera

Family: Delphacidae

Genus: Megamelus Fieber, 1866

Species: scutellaris Berg, 1883

The genus Megamelus is widespread throughout the world and includes 

24 species in the Americas (Asche, 1985). Most species in this genus are 

associated with aquatic plants (O’Brien and Wilson, 1985). Two of the 

South American species, M. electrae in Trinidad and Tobago (Cruttwell,

1973) and M. scutellaris in Peru, Brazil, Uruguay, and Argentina (Sosa et

al., 2004), are associated with water hyacinth. 

1. Chemical 

Control

2. Mechanical 

Control

3. Biological 

Control

1. Description
4

Megamelus scutellaris produces multiple, over-lapping generations per 

year. Adults exhibit two wing forms with a long-winged dispersal form,

which is capable of flight (macropterous), and a short-winged, non-flying 

form (brachypterous). The wing form is determined within the generation 

and is dependent on environmental cues, such as crowding and host plant 

quality. The macropterous form enables the insect to disperse from 

overcrowded or poor quality plants to find better quality water hyacinth

plants.

Adults mate at the bottom of the water hyacinth plant (Sosa et al., 2005),

as well as on the upper leaves (Tipping et al., 2008). A few days after 

mating, females begin laying eggs (ovipositing) within plant tissue located 

in the leaves of water hyacinth. Most egg laying (oviposition) sites 

contain two eggs (Tipping et al., 2008). Eggs are oval with one end 

pointed and the other end rounded. They are milky white when laid, and 

turn yellowish white with reddish eye spots before hatching (Sosa et al.,

2005).

Nymphs (immature insect stage) emerge after 7 to 13 days after eggs are 

laid (Sosa et al., 2005; Tipping et al., 2008), depending upon the 

temperature. The emerging nymph begins feeding on the plant closest to 

the water surface. Nymphs develop through five instars (life stages 

between molts), and will feed on the top and bottom of leaves and leaf 

stems. Development of the entire immature stage in outdoor conditions 

can take about 25 days (Sosa et al., 2005). Field observations in Argentina 

have found that the immature stages of M. scutellaris overwinter in 

decayed mats of water hyacinth (Sosa et al., 2005).

Planthoppers, such as M. scutellaris, feed by inserting their stylets 

(needle-like mouthparts) into the plant and ingesting the sap (Sogawa,

1982). Saliva is secreted during penetration, forming a stylet sheath which

acts to hold the stylets together, and facilitate lubrication and movement 

toward food sources (Sogawa, 1982). The sheath remains imbedded in the 

tissue after the stylets are withdrawn and may be branched or unbranched,

depending upon whether or not the stylets changed direction within the 

plant after insertion. Spiller (1990) found that stylet probing caused 

significant damage to cell organs, leading to cell death.

The native range of M. scutellaris includes Argentina—Buenos Aires, 

Chaco, Corrientes, Entre Rios, Formosa, and Santa Fe Provinces; Brazil—

Rio de Janeiro, Sao Paulo, Paraná, and Río Grande do Sul States; Peru—

Iquitos; and Uruguay. According to Sosa et al. (2004) the native range is 

likely to be much more extensive in South America wherever water 

hyacinth occurs naturally. M. scutellaris is not known to have been 

introduced into any countries outside its native range, although it has been 

studied in South African quarantine. The expected range of M. scutellaris

2. Life History

3. Native Range
5

in North America should mirror that of water hyacinth (Tipping et al. 

2008).

In quarantine studies, water hyacinth plants are heavily damaged by M. 

scutellaris feeding, and they eventually wilt and die. Water hyacinth

plants without M. scutellaris grew larger and produced more leaves than 

plants attacked by the insects. Quarantine study data indicate the potential 

of M. scutellaris to damage water hyacinth, and to rapidly increase in 

number in a relatively short time (Tipping et al., 2008).

III. Affected Environment

Water hyacinth is a floating plant. Plants vary in size from a few 

centimeters (cm) to over a meter in height. The glossy green, leathery leaf 

blades are up to 20 cm long and 5 to 15 cm wide, and are attached to stems

that are often spongy-inflated. Numerous dark, branched, fibrous roots 

dangle in the water from the underside of the plant. The flower is showy 

light-blue to violet (sometimes white) on a loose terminal spike. Each 

flower has six bluish-purple petals joined at the base to form a short tube. 

One petal bears a yellow spot. The fruit is a three-celled capsule 

containing many tiny, ribbed seeds. 

In spring, overwintering water hyacinth plants (old stem bases) initiate 

growth by producing daughter plants. These plants slowly increase in 

number and size during the spring and summer until the maximum 

biomass is reached in September. As the plants become crowded, shading 

causes many of the lower leaves to die back. In mild climates, water 

hyacinth can flower year-round, and from early spring to late fall 

elsewhere. Seeds form in the submerged, withered flower. By late fall,

some of the old leaves start dying and by January most plants have 

declined. Colonization of a new site begins with small plants at low plant 

densities. These plants increase in number and density without increasing 

in size until they produce a new mat. As a mature dense mat is formed, 

individual plant size continues to increase, however, density decreases.

Water hyacinth reproduces sexually by seeds (Müller, 1883), and 

vegetatively by budding and stolons (a shoot which bends to the ground or 

which grows horizontally above the ground and produces roots and shoots 

at the nodes). Daughter plants sprout from the stolons, and doubling times 

of mats have been reported from 6 to 18 days (Mitchell, 1976). The seeds 

can germinate in a few days or remain dormant for 15 to 20 years

(Matthews, 1967; Gopal, 1987); however, they usually sink and remain 

dormant through periods of stress (droughts). Upon reflooding, the seeds 

often germinate and renew the growth cycle. 

4. Impact on 

Water 

Hyacinth
6

A. Areas Affected by Water Hyacinth

Water hyacinth is native to South America, but has been introduced

throughout much of the tropics and subtropics. The center of origin is 

unknown but is thought to be Amazonia. It is also common in the 

Caribbean. In Africa, it has infested the Nile, Congo, and Zaire River 

watersheds. It also occurs in Senegal, the Central African Republic, South 

Africa, and Madagascar. It is common in tropical Asia, including 

Southeast Asia, most of the Indian subcontinent, and extends through 

coastal China into South Korea and Japan. It is also found throughout 

Indonesia and in Australia. 

Water hyacinth is believed to have been introduced into the United States

in 1884 at an exposition in New Orleans. Within 70 years of reaching 

Florida, the plant covered 126,000 acres of waterways (Schmitz et al.,

1993). Worldwide, the limits of distribution are at 40° North and South

latitude. In the United States, water hyacinth is most abundant in the 

southeastern United States. It also occurs in California and Hawaii, with 

scattered records in other States. Water hyacinth has been reported in 

Oregon, Washington, Illinois, Maryland, New Jersey, Kentucky, 

Tennessee, Missouri, and Arkansas where plants escape summertime 

cultivation but do not persist through the winter. It is annually stocked in 

farm fish ponds in southern Arizona and southern Delaware, but has not 

become established in the natural systems of these States.

Water hyacinth is an aquatic weed which can be found in lakes, rivers, 

ponds, and ditches of temperate climates. It is not winter-hardy; its 

minimum growth temperature is 12 oCelsius (C) (54 oFahrenheit (F)); its 

optimum growth temperature is 25 to 30 oC (77 to 86 oF); its maximum 

growth temperature is 33 to 35 oC (92 to 95 oF) (Kasselmann, 1995).

B. Plants Related to Water Hyacinth and Their 

Distribution

Information regarding plants taxonomically related to water hyacinth is 

included because native plant species which are closely related to water 

hyacinth have the most potential to be attacked by M. scutellaris.

Water hyacinth is a member of the pickerelweed family (Pontederiaceae). 

The families most closely related to the Pontederiaceae are—

Commelinaceae, Haemodoraceae, Philydraceae, and Hanguanaceae. 

There are 6 to 9 genera and 30 to 40 species in the Pontederiaceae 

worldwide (table 1). Most members of this family are confined to the 

Americas, and all members of the genus Eichhornia (8 species) originate 

in tropical America, except for E. natans, which is from tropical Africa. 

Horn (2002) recognizes 13 species (including E. crassipes) in 4 genera

that occur in the United States (table 2). Four of these (E. azurea, E. 

2. Present 

Distribution in 

North America

1. Taxonomically 

Related Plants

1. Native and 

Worldwide 

Distribution

3. Habitat
7

crassipes, E. paniculata, and Monochoria vaginalis) are not native to 

North America. Two of the 13 (E. paniculata and the native Heteranthera 

peduncularis) have been collected in the United States only once, each 

about a century ago. Pickerelweed (Pontederia cordata) is sometimes 

separated into two varieties, P. cordata var. cordata and P. cordata var. 

lancifolia, based mainly on leaf shape. However, leaf shape is variable

(even within an individual) and seems to be influenced by habitat 

conditions; therefore, this distinction is poorly justified.

 

Table 1. Worldwide Distribution of Species of Pontederiaceae

Species*

Eichhornia crassipes Mart. (Solms)

Distribution†

NA, CA, SA, AFR, ASIA

Eichhornia azurea (Sw.) Kunth NA, CA, SA

Eichhornia cordifolia Gand. CA

Eichhornia diversifolia (Vahl) Urban NA, CA, SA

Eichhornia heterosperma Alexander CA, SA

Eichhornia natans (P. Beauv.) Solms AFR

Eichhornia paniculata (Sprengl) Solms CA, SA

Eichhornia paradoxa (Mart.) Solms CA, SA

Heteranthera callifolia Rchb. ex Kunth AFR

Heteranthera (=Zosterella) dubia (Jacq.) MacMillan NA, CA, AFR

Heteranthera limosa (Sw.) Willd. NA, CA, SA

Heteranthera mexicana S. Watson NA

Heteranthera multiflora (Griseb.) C.N. Horn NA

Heteranthera oblongifolia C. Mart. ex Roem. & Schult. SA

Heteranthera penduncularis Benth. NA

Heteranthera reniformis Ruiz López & Pavón NA

Heteranthera rotundifolia (Kunth) Griseb. NA, CA, SA

Heteranthera seubertiana Solms CA

Heteranthera spicata J. Presl. CA, SA

Heteranthera zosterifolia Mart. SA

Hydrothrix gardneri Hook. f. SA

Monochoria africana (Solms-Laub.) N.E. Br. AFR

Monochoria australasica Ridley AUS

Monochoria brevipetiolata Verdc. AFR

Monochoria elata Ridl. ASIA

Monochoria hastata (L.) Solms SA, ASIA

Monochoria korsakowii Regel & Maack ASIA

Monochoria plantaginea Kunth ASIA

Monochoria vaginalis (Burm. f.) K. Presl ex Kunth NA, ASIA

Pontederia cordata L. NA, CA, SA

Pontederia crassicaulis Schlecht CA

Pontederia lagoensis Warm. SA

Pontederia parviflora Alexander CA

Pontederia (=Reussia) rotundifolia L.f. CA, SA

Pontederia sagittata C. Presl CA

Pontederia subovata (Seub.) Lowden SA

Reussia triflora Seub. SA

Scholleropsis lutea H. Perr. AFR

*

Based on data from Eckenwalderand Barrett (1986), Horm (2002), IOPI (2002) NS MBG (2002).

† Africa (AFR), South America (SA), Central America—including southern Mexico (CA), North America 

(NA), Europe (EU), Australia (AUS), and Asia (ASIA).
8

Table 2. Species of Pontederiaceae in the United States.*

Non-native (Introduced) Species State Status

Eichhornia azurea (Sw.) Kunth

Eichhornia crassipes (Martius) Solms-Laubach

Eichhornia paniculata (Sprengl.) Solms‡

Monochoria vaginalis (Burm. f.) K. Presl ex Kunth

Native Species

Eichhornia diversifolia (Vahl) Urban†

Heteranthera (=Zosterella) dubia (Jacq.) MacMillan Special concern in 

Kentucky, threatened in 

Maine, endangered in 

New Hampshire

Heteranthera limosa (Sw.) Willd. Special concern in 

Kentucky, threatened in 

Minnesota and 

Tennessee

Heteranthera (=Eurystemon) mexicana S. Watson

Heteranthera multiflora (Griseb.) C.N. Horn Threatened in 

Pennsylvania

Heteranthera peduncularis Benth.‡

Heteranthera reniformis Ruiz López & Pavón Special concern in 

Connecticut, endangered 

in Illinois and Ohio

Heteranthera rotundifolia (Kunth) Griseb.

Pontederia cordata L.

* Derived from USDA (1997), but modified according to Horn (2002).

†

Native to Puerto Rico (Horn, 2002).

‡

Known from only a single collection about 100 years ago (Horn, 2002).

IV. Environmental Consequences 

A. No Action

Water hyacinth grows rapidly, forming expansive colonies of tall, 

interwoven floating plants. It blankets large water bodies, creating 

impenetrable barriers and obstructing navigation. Floating mats block 

drainage, causing flooding or preventing floodwaters from subsiding. 

Large rafts of water hyacinth plants accumulate where water channels 

narrow, sometimes causing bridges to collapse. Water hyacinth hinders 

irrigation by impeding water flow, by clogging irrigation pumps, and by 

interfering with weirs (a low dam built across a stream to raise its level or 

divert its flow). Multimillion-dollar flood control and water supply 

projects can be rendered useless by water hyacinth infestations

(Gowanloch and Bajkov, 1948).

Infestations block access to recreational areas and decrease waterfront 

property values, often harming the economy of communities that depend 

upon fishing and water sports for revenue. Shifting water hyacinth mats 

sometimes prevents boats from reaching shore, trapping the occupants and 

exposing them to environmental hazards. Water hyacinth infestations 

intensify mosquito problems by hindering insecticide applications, 

1. Impact of 

Spread of 

Water 

Hyacinth
9

interfering with predators, increasing habitat for species that attach to 

plants, and impeding runoff and water circulation. 

Dense mats reduce light to submerged plants, thus depleting oxygen in 

aquatic communities. The resultant lack of phytoplankton (very small,

free-floating plants) alters the composition of invertebrate communities, 

ultimately affecting fisheries. Drifting mats scour vegetation, destroying 

native plants and wildlife habitat. Water hyacinth also competes with 

other plants, often displacing wildlife forage and habitat. Higher sediment 

loading occurs under water hyacinth mats due to increased production of 

detritus and siltation.

The continued use of chemical herbicides, mechanical controls, and 

previously released biological control agents at current levels would result 

if the ―no action‖ alternative is chosen, and may continue even if permits 

are issued for environmental release of M. scutellaris.

a. Chemical Control

Herbicidal treatment of water hyacinth often damages nearby desirable 

vegetation, and treatment is costly. Cost of treatment depends on the size 

of the treatment area, the scale of the treatment, and the herbicide dosage. 

Current costs per acre range from $250 for glyphosate, and for 2,4-D, 

between $300 to $1,000 (Gibbons et al., 1999). Use of herbicides in 

aquatic areas also raises water quality concerns. After herbicide 

application, massive amounts of dying vegetation can reduce the amount 

of oxygen in the water column.

b. Mechanical Control

Mechanical harvesting of water hyacinth often damages nearby desirable 

vegetation. This method is better suited to small, isolated drainages, and 

all plant fragments must be removed to avoid re-sprouting. Harvesting 

costs can range from $500 to $800 per acre, with additional costs for 

mobilization and equipment ($35,000 to $111,000) (WSDE, 2001). There 

may be additional fees for disposal of plant material. 

c. Biological Control

The previously released water hyacinth biological control insects

Neochetina eichhorniae, N. bruchi, and Niphograpta albigutallis now 

occur throughout the range of water hyacinth (Center et al., 1999b). 

Numerous field studies documented the decline of water hyacinth in 

diverse geographical areas of the United States after introductions of 

biological control agents (Goyer and Stark, 1984; Cofrancesco et al., 

1985). Surveys conducted by Center et al. (1999a) confirmed that water 

hyacinth populations not subjected to repeated control operations become 

2. Impact from 

the Use of 

Other Control

Methods
10

stressed by biological control agents, particularly by the two Neochetina

species. However, herbicide programs periodically disrupt the life cycles 

of the currently released biological control organisms and limit their 

potential. This is because the food source of the insect is killed by the 

herbicide, and their ability to disperse to untreated plants is limited. As a 

result, more mobile agents with higher reproductive capacities are needed 

that can survive disruptions of water hyacinth communities by herbicide 

applications.

 

These environmental consequences may occur even with the 

implementation of the biological control alternative, depending on the 

efficacy of M. scutellaris to reduce water hyacinth in the continental 

United States. 

B. Issue Permits for Environmental Release of M.

scutellaris

Host specificity to water hyacinth has been demonstrated through field 

observations and host specificity testing. 

a. Scientific Literature

In the scientific literature, specificity of M. scutellaris has been found to 

be limited to species in the family Pontederiaceae. In no-choice3

laboratory tests, potential hosts of M. scutellaris included Pontederia 

cordata var. cordata and P. rotundifolia. However, in field explorations 

in which the two species coexisted with water hyacinth, M. scutellaris was 

only found on water hyacinth (Sosa, 2007a). In addition, field surveys 

were conducted from 1997 to 2000 to examine several plant species in the 

plant family Pontederiaceae for the presence of M. scutellaris. Species 

included Pontederia cordata, P. rotundifolia, P. subovata, P. parviflora, 

water hyacinth, and Eichornia azurea, but M. scutellaris was only 

collected from water hyacinth (Sosa, 2007b). 

b. Host Specificity Testing

Host range determination of M. scutellaris was based on plant species in 

seven categories listed in table 3, including representatives from the 

Pontederiaceae (Tipping et al., 2008). Additionally, native and exotic 

associated wetland species and economic species were also tested.

 

3 A no-choice test is when M. scutellaris is placed into a cage in which only the test 

plants (non-target plants) are present for feeding or egg laying. In a choice test, M. 

scutellaris is offered a choice between water hyacinth and the test plant in the cage.

1. Impact of 

M. scutellaris 

on Non-target 

Plants
11

Table 3. Seven Categories of Plants Considered for the Test Plant List. 

These plants were used for host specificity tests using M. scutellaris and 

were conducted in quarantine facilities.

Category 1—Genetic Type of the Target Weed Species (water hyacinth).

Genus and Species Common Name N. American Status

Eichhornia crassipes (Mart.) Solms-Laub. Water hyacinth Exotic

Category 2—Species in the Same Genus (Eichhornia) as Water Hyacinth.

(There are no native North American species of Eichhornia, except E. paniculata

from southern Mexico.) 

Genus and Species Common Name N. American Status

Eichhornia paniculata (Spreng.) Solms Brazilian water 

hyacinth

Introduced into Florida

Eichhornia diversifolia (Vahl) Urb. Variableleaf water 

hyacinth

Native to Puerto Rico

Category 3—Species in Other Genera but in the Same Family.

(Pontederiaceae) and subfamily as water hyacinth.

Genus and Species Common Name N. American Status

Heteranthera dubia (Jacquin) MacMillan grassleaf mudplantain Native

Heteranthera limosa (Sw.) Willd. blue mudplantain Native

Heteranthera multiflora (Griseb.) Horn bouquet mudplantain Native

Heteranthera peduncularis Benth. egret mudplantain Native

Heteranthera reniformis Ruiz & Pavón kidneyleaf 

mudplantain

Native

Heteranthera rotundifolia (Kunth) 

Griseb.

roundleaf mudplantain Native

Heteranthera zosterfolia C. Martius Stargrass Exotic

Monochoria vaginalis (Burman f.) C. 

Presl ex Kunth

heartshape false 

pickerelweed

Exotic

Pontederia cordata L. Pickerelweed Native

Category 4—Threatened and Endangered Species in the Same Family as 

Water Hyacinth.

There are no federally listed threatened or endangered species in the plant 

family Pontederiaceae.

Category 5—Species in the Same Order (Pontederiales) as Water Hyacinth.

Family, Genus, and Species Common name N. American Status

Commelinaceae, Commelina erecta L. Dayflower Native

Commelinaceae, Commelina 

benghalensis L.

Benghal dayflower Exotic

Commelinaceae, Tradescantia ohiensis 

Raf.

Bluejacket Native
12

Category 6—Species in Orders Other than Water Hyacinth.

According to Dahlgren et al. (1981; see also Barrett and Graham, 1997),

the Pontederiales are most closely related to the orders Haemodorales (2

native species in 2 genera—Lachnanthes and Xiphidium), Philydrales (no 

North American natives), and Typhales (22 native species in 2 genera—

Typha and Sparganium). Other wetland species commonly found in close 

association with water hyacinth were included in host specificity testing. 

In addition, common exotic plant species were evaluated for their 

suitability for M. scutellaris.

Order Family Genus Species Common Name Status

Alismatales Alismataceae Sagittaria falcata Duck potato Native

Alismatales Alismataceae Sagittaria latifolia

Broadleaf 

arrowhead Native

Alismatales Alismataceae Echinodorius cordifolus Spade leaf sword Native

Liliales Amaryllidaceae Crinum americanum Swamp lily Native

Apiales Apiaceae Hydrocotyle umbellata Marsh pennywort Native

Arales Araceae Peltandra virginica Green arum Native

Arales Araceae Pistia stratiotes Water lettuce Exotic

Arales Araceae Orontium aquaticum Golden club Native

Arales Araceae Colocasia esculenta Taro Exotic

Hydropteridales Azollaceae Azolla caroliniana

Carolina mosquito 

fern Native

Zingiberales Cannaceae Canna flaccida Golden canna Native

Zingiberales Costaceae Costus woodsonii Red button ginger Exotic

Capparales Cruciferae Nasturtium aquaticum Watercress Exotic

Eriocaulales Eriocaulaceae Eriocaulon compressum Flattened pipewort Native

Fabales Fabaceae Glycine max Soybean Crop

Cyperales Graminaceae Oryza sativa Rice Crop

Haloragales Haloragaceae Proserpinaca palustris Mermaid weed Native

Haloragales Haloragaceae Myriophyllum aquaticum Parrot feather Native

Hydrocharitales Hydrocharitaceae Limnobium spongia Frog's bit Native

Liliales Iridaceae Iris hexagona Prairie iris Native

Arales Lemnaceae Lemna minor

Common 

duckweed Native

Zingiberales Marantaceae Thalia geniculata Alligator flag Native

Hydropteridales Marsileaceae Marsilea quadrifolia

European 

waterclover Exotic

Solanales Menyanthaceae Nymphoides aquatica Floating hearts Native

Fabales Mimosaceae Neptunia oleraceae Sensitive plant Exotic

Musales Musaceae Musa acuminate Dwarf banana Crop

Nymphaeales Nymphaeaceae Nuphar luteum Spatterdock Native

Nymphaeales Nymphaeaceae Nymphaea odorata Fragrant water lily Native

Nymphaeales Nymphaeaceae Nymphaea mexicana Yellow water lily Native

Myrtales Onagraceae Ludwigia glandulosa Primrose-willow Native

Myrtales Onagraceae Ludwigia peploides Water primrose Native

Orchidales Orchidaceae Epidendrum sp. Crop

Orchidales Orchidaceae Vanilla planifolia Vanilla Crop

Orchidales Orchidaceae Dendrobium sp. Crop
13

Order Family Genus Species Common Name Status

Poaceae Poaceae Triticum aestivum Wheat Crop

Poaceae Poaceae Saccharum officinarum Sugarcane Crop

Poaceae Poaceae Sorghum bicolor Sorghum Crop

Cyperales Poaceae Zizaniopsis miliacea Southern wild rice Native

Piperales Saururaceae Saururus cernuus Lizard's tail Native

Scrophulariales Scrophulariaceae Bacopa caroliniana Blue hyssop Native

Scrophulariales Scrophulariaceae Bacopa monnieri

Smooth water 

hyssop Native

Solanales Solanaceae Lycopersicon esculentum Tomato Crop

Typhales Typhaceae Typha latifolia Cattail Native

Zingiberales Zingiberaceae Renealmia cernua Red renealmia Exotic

Zingiberales Zingiberaceae Alpina nutans Shell ginger Exotic

Zingiberales Zingiberaceae Curcuma zedoaria Tumeric Exotic

Zingiberales Zingiberaceae Zingiber officinale Ginger Exotic

Zingiberales Zingiberaceae Hedychium coronarium Garland lily Exotic

Category 7—Any Species on which M. scutellaris Or Its Close Relatives Are 

Found.

Plant Order, Family, Genus,

and Species

Megamelus scutellaris

relatives (same genus)

Status in 

N. America

Nymphaeales, Nymphaeaceae, 

Nymphaeae ordorata

M. davisii Van Duzee Native

Nymphaeales, Nymphaeaceae, 

Nuphar luteum

M. davisii Van Duzee Native

Commelinales, Pontederiaceae, 

Pontederia cordata

M. palaetus (Van Duzee)

M. bellicus

Native

Exotic

Hydrocharitales, Hydrocharitaceae,

Limnobium spongia

M. timehri Native

c. Laboratory Tests

(1) Oviposition Testing 

In no-choice oviposition testing, in which M. scutellaris is provided only 

non-target plants as an oviposition choice, adults did oviposit into other 

non-target plant species before they died and nymphs did emerge from 

five species. Oviposition occurred on Eichhornia paniculata (exotic), 

Heteranthera dubia (native), H. rotundifolia (native), Monochoria 

vaginalis (exotic), and Pontederia cordata (native) (appendix 1). All of 

these species occur within the same genus or subfamily as water hyacinth. 

The species and the mean ( standard error (SE)) number of emerged 

nymphs were Eichhornia paniculata (17.2 4.7), Heteranthera dubia (4.4 

1.7), H. rotundifolia (2.7 2.7), Monochoria vaginalis (6.0 + 4.3), and 

Pontederia cordata (0.2 0.2). In contrast, 143.2 6.6 nymphs emerged 

per water hyacinth plant. 
14

In choice oviposition tests, where M. scutellaris was provided a choice of 

either the non-target host plant or water hyacinth for oviposition, three 

close relatives were tested—Eichhornia paniculata, Heteranthera 

rotundifolia, and Pontederia cordata (appendix 2). Nymph emergence 

occurred only on E. paniculata and P. cordata. 

(2) Feeding and Survival Testing 

To test the potential for M. scutellaris to feed on non-target plants if water 

hyacinth were removed from a site by flooding, drought, or herbicides (a 

spill-over event), large-nymph transfer tests were conducted. Fifty-nine 

plants were tested to evaluate large-nymph survival for 7 days. Ten 

plants, 6 in the Pontederiaceae, supported some survival of large nymphs 

for 7 days (appendix 3). All test species which supported large nymph 

survival for 7 days were tested using small nymphs, as well as P. cordata. 

Small nymphs were able to survive and develop only on H. dubia and E.

paniculata (appendix 4). Only a single nymph survived on H. dubia after 

21 days, and it failed to develop into an adult. Only one nymph was able 

to develop to adulthood on E. paniculata, although most of the surviving 

nymphs did develop into larger nymphs. 

Emerged nymphs were transferred to non-target plant species (appendix 

4). A mean percentage ( SE) of 78.2 1.1 percent of nymphs survived to 

adulthood on water hyacinth while none survived on the other non-target 

transfer plants except for E. paniculata, where 37.5 percent survived to 

adulthood. Those adults were unable to survive on E. paniculata for more 

than a few days, while 92.3 percent of those adults survived on water 

hyacinth during the same period.

(3) Discussion

 

Megamelus scutellaris was unable to sustain populations on any test plant. 

It is also unlikely to cause problems during spill-over events that may be 

triggered by perturbations, such as herbicide application, because survival 

was virtually nonexistent on associated wetland plants regardless of 

taxonomic distances. It might be possible for displaced adults or nymphs 

to temporarily feed on the native plant H. dubia (grassleaf mudplantain) 

should the plant be nearby and have foliage floating on the surface. The 

majority of biomass in this species is submerged and, therefore, any minor 

feeding is unlikely to damage the plant. 

Heteranthera dubia did not support development of M. scutellaris to 

adulthood. The greatest amount of survival occurred on the exotic species 

E. paniculata (Brazilian water hyacinth), which is also a suboptimal host. 

The native aquatic plant P. cordata (pickerelweed) was an unsuitable host 

because adults and nymphs were unable to survive on it for 7 days.
15

(4) Accidental Transmission of Plant Viruses

Some insects in the family Delphacidae can transmit viruses from one 

plant to another. Of the 1,100 known delphacid species, only 27 species 

have been documented to experimentally transmit plant viruses (Nault,

1994). 

There is no evidence of M. scutellaris transmitting any virus diseases

within or without the water hyacinth system. Water hyacinth pathogens 

(fungi, such as Uredo eichhorniae (Charudattan, 2001)) have received a 

great deal of attention over the decades from researchers seeking 

biological antagonists for this weed; however, there are no records of 

viruses or virus-like diseases in water hyacinth. 

Once a biological control agent, such as M. scutellaris, is released into the 

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

could move from the target plant (water hyacinth) to attack non-target

plants, such as the native plant P. cordata or H. dubia. Host shifts by 

introduced weed biological control agents to unrelated plants are rare 

(Pemberton, 2000). Native species closely related to the target species are 

the most likely to be attacked (Louda et al., 2003). If other plant species 

were to be attacked by M. scutellaris, the resulting effects could be 

environmental impacts that may not be easily reversed. Biological control 

agents, such as M. scutellaris, 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, these agents may not be successful in reducing water hyacinth

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 water hyacinth by M. scutellaris will 

not be known until after release occurs and post-release monitoring has 

been conducted.

―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).

In the late 1890s, water hyacinth was beginning to block navigable waters 

in several Southern States. In 1899, Congress authorized the U.S. Army 

Corps of Engineers (USACE) to remove water hyacinth from navigable 

waters in Florida and Louisiana. Because of its persistence, water 

hyacinth removal from waterways became an ongoing function of the 

USACE. Herbicide and biological control research is being conducted for 

2. Uncertainties 

Regarding the 

Environmental 

Release of 

M. scutellaris 

3. Cumulative 

Impacts
16

USACE by USDA at Ft. Lauderdale, Florida. Since 1960, a cooperative 

program with the State of Florida Game and Fresh Water Fish 

Commission has been in place to control water hyacinth. 

In Texas, the Texas Parks and Wildlife Department controls water 

hyacinth throughout Texas using mechanical controls and herbicides. 

In California, State legislation in 1982 designated Cal Boating as the lead 

agency for controlling water hyacinth in the Sacramento-San Joaquin 

Delta, its tributaries, and the Suisun Marsh. Herbicides are used to control 

water hyacinth.

In Louisiana, the Louisiana Department of Wildlife and Fisheries is 

charged with the responsibility of controlling water hyacinth in 

Louisiana’s public waters. Chemical control began in 1946, and 

biological controls are used. Biological control agents were first 

introduced into Louisiana in 1974 (Manning, 1979).

Release of M. scutellaris is not expected to have any negative cumulative 

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

water hyacinth. Effective biological control of water hyacinth will have 

beneficial effects for weed management programs, and may result in a 

long-term, non-damaging method to assist in the control of water hyacinth, 

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. 

APHIS has determined that, based on the host specificity of M. scutellaris, 

there will be no effect on any listed plant or designated critical habitat in 

the continental United States. In host specificity testing, the biological 

control organism oviposited and nymphs survived only on plants within 

the same genus or subfamily as water hyacinth. No federally listed 

threatened or endangered plants belong to the family Pontederiaceae

(USFWS, TESS, 2009). In addition, no federally listed threatened or 

endangered species are known to depend on or use water hyacinth. 

4. Endangered 

Species Act
17

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 M. 

scutellaris, and their 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 

M. scutellaris.

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....‖ In June 2009, APHIS 

sent out letters to potentially affected tribal leaders and organizations to 

give notification of the proposed environmental release of M. scutellaris

and to request input from tribes. APHIS will continue to consult and 

collaborate with Indian tribal officials to ensure that they are wellinformed and represented in policy and program decisions that may impact 

their agricultural interests, in accordance with EO 13175.
18

VI. Agencies, Organizations, and 

Individuals Consulted

The Technical Advisory Group for the Biological Control Agents of 

Weeds (TAG) recommended the release of M. scutellaris on February 2, 

2009. TAG members that reviewed the release petition (Tipping et al.,

2008) included representatives from the Bureau of Indian Affairs, 

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

Geological Survey, Environmental Protection Agency, California 

Department of Food and Agriculture, U.S. Army Corps of Engineers, 

Bureau of Reclamation, U.S. Forest Service, and Agriculture and AgriFood Canada, Health Canada. 

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 and Risk Analysis Services

4700 River Road, Unit 149

Riverdale, MD 20737

U.S. Department of Agriculture

Animal and Plant Health Inspection Service

Plant Protection and Quarantine 

Registrations, Identification, Permits, and Plant Safeguarding

4700 River Road, Unit 133

Riverdale, MD 20737

U.S. Department of Agriculture

Agricultural Research Service

Invasive Plants Research Lab

3205 College Avenue

Fort Lauderdale, FL 33314
19

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A–1

Appendix A. Results of No-choice Oviposition Tests

Two females and one male M. scutellaris (7 to 10 days of age) were placed on single plants for a 

period of 7 days. The percentage of adults (%P1 Survival), the number of emerged F1 nymphs 

(No. Progeny), and their survival (% F1 Nymph Survival) were recorded or calculated. All tests 

involving non-target plant species were replicated four times. Shaded rows indicate plant species 

oviposited on by M. scutellaris and nymphs emerged. Nymphs survived only on the exotic plant 

Eichhornia paniculata.

% P1 Survival No. Progeny % F1 Nymph Survival

Test 

Species

Water 

Hyacinth

Test 

Species

Water 

Hyacinth

Test 

Species

Water 

Hyacinth

Genus Species Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE

1 Commelina benghalensis 0.0 0.0 91.7 8.3 0.0 0.0 36.5 4.9 - - - -

2 Commelina erecta 0.0 0.0 93.9 3.8 0.0 0.0 200.6 31.7 - - - -

3 Eichhornia diversifolia 0.0 0.0 93.9 3.8 0.0 0.0 200.6 31.7 - - - -

4 Eichhornia paniculata 8.3 8.3 100.0 0.0 17.2 4.7 176.0 10.7 1.1 1.1 82.5 0.7

5 Heteranthera dubia 0.0 0.0 93.9 3.8 4.4 1.7 200.6 31.7 0.0 0.0 - -

6 Heteranthera multiflora 0.0 0.0 91.7 8.3 0.0 0.0 89.5 13.1 - - - -

7 Heteranthera reniformis 0.0 0.0 93.9 3.8 0.0 0.0 200.6 31.7 - - - -

8 Heteranthera rotundifolia 0.0 0.0 91.7 8.3 2.7 2.7 89.5 13.1 0.0 0.0 - -

9 Heteranthera zosterfolia 0.0 0.0 93.9 3.8 0.0 0.0 200.6 31.7 - - - -

10 Monochoria vaginalis 0.0 0.0 91.7 8.3 6.0 4.3 89.5 13.1 0.0 0.0 - -

11 Pontederia cordata 0.0 0.0 91.7 8.3 0.2 0.2 113.7 26.8 0.0 0.0 50.0 7.0

12 Echinodorus chordifolus 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

13 Sagittaria falcate 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

14 Sagittaria latifolia 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

15 Crinum americanum 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

16 Hydrocotyle umbellate 0.0 0.0 91.7 8.3 0.0 0.0 36.5 4.9 - - - -

17 Colocasia esculenta 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

18 Orontium aquaticum 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

19 Peltandra virginica 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

20 Azolla caroliniana 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

21 Canna flaccida 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

22 Nasturtium aquaticum 0.0 0.0 91.7 8.3 0.0 0.0 113.7 26.8 - - 50.0 7.0

23 Eriocaulon compressum 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

24 Proserpinaca palustris 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

25 Limnobium spongia 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

26 Iris hexagona 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

27 Lemna minor 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

28 Thalia geniculata 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

29 Marsilea mutica 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

30 Nymphoides aquatica 0.0 0.0 91.7 8.3 0.0 0.0 36.5 4.9 - - - -

31 Neptunia aquatica 0.0 0.0 91.7 8.3 0.0 0.0 113.7 26.8 - - 50.0 7.0
A–2

% P1 Survival No. Progeny % F1 Nymph Survival

Test 

Species

Water 

Hyacinth

Test 

Species

Water 

Hyacinth

Test 

Species

Water 

Hyacinth

Genus Species Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE

32 Nelumbo lutea 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

33 Nuphar luteum 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

34 Nymphaea oderata 0.0 0.0 91.7 8.3 0.0 0.0 113.7 26.8 - - 50.0 7.0

35 Nymphaea mexicana 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - 92.3 4.8

36 Ludwigia glandulosa 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

37 Ludwigia peploides 0.0 0.0 91.7 8.3 0.0 0.0 113.7 26.8 - - - -

38 Dendrobium sp. 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

39 Epidendrum sp. 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

40 Vanilla planifolia 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

41 Saururus cernuus 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

42 Bacopa caroliniana 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - - -

43 Bacopa monnieri 0.0 0.0 91.7 8.3 0.0 0.0 113.7 26.8 - - - -

44 Typha latifolia 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - - -

45 Costus woodsonii 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

46 Glycine max 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

47 Oryza sativa 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

48 Musa sp. 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - - -

49 Saccharum officinarum 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

50 Sorghum bicolor 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - - -

51 Triticum aestivum 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - - -

52 Zea mays 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

53 Lycopersican esculentum 0.0 0.0 100.0 0.0 0.0 0.0 176.0 10.7 - - 82.5 0.7

54 Alpina natans 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

55 Globba schomburkii 0.0 0.0 83.4 16.6 0.0 0.0 154.5 22.9 - - - -

56 Hedychium coronarium 0.0 0.0 91.7 8.3 0.0 0.0 164.0 24.4 - - - -

57 Renealmia cernua 0.0 0.0 91.7 8.3 0.0 0.0 89.5 13.1 - - - -

Source: Tipping, et al., 2008.
B–1

Appendix B. Results of Choice Oviposition Testing 

Two females and one male M. scutellaris (7 to 10 days of age) were placed in an aquarium with 

a single non-target test plant and a single water hyacinth plant of similar size for a period of 7

days. The number of emerged nymphs (No. Progeny), their percent survival (%F1 Nymph 

Survival), and the percent survival of adults (%F1 Adult Survival) were recorded or calculated. 

All tests were replicated four times. Adults emerged only from Eichhornia paniculata.

Source: Tipping, et al., 2008.

No. Progeny % F1 Nymph Survival % F1 Adult Survival

Genus Species Test 

Species

Water 

Hyacinth

Test 

Species

Water 

Hyacinth

Test 

Species

Water 

Hyacinth

Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE

Eichhornia paniculata 1.5 0.9 121.5 14.6 37.5 12.5 82.5 8.5 0.0 0.0 92.3 4.8

Heteranthera rotundifolia 0 0.0 57.2 22.9 0.0 0.0 84.5 1.3 - - - -

Pontederia cordata 0.3 0.3 168.5 16.9 0.0 0.0 85.0 2.8 - - - -
C–1

Appendix C. Results of No-choice Large Nymph 

Transfer Tests (spill-over scenario)

Ten 3rd to 5

th instars were placed on single test plants in sleeve cages for 7 days. The 

number of surviving life stages were tallied after 7 days, and the percentage of large nymph 

survival was calculated. Tests were replicated at least four times. Shaded rows indicate 

species that supported some survival of large nymphs for 7 days.

% Large Nymph Survival

Number 

Tested

Test Species Number

Tested

Water 

Hyacinth

Family Genus Species Mean SE Mean SE

1 Commelinaceae Commelina bengalensis 40 0.0 0.0 40 87.5 0.6

2 Commelinaceae Commelina erecta 50 0.0 0.0 50 28.0 13.0

3 Commelinaceae Tradescantia ohiensis 50 0.0 0.0 50 96.0 5.0

4 Pontederiaceae Eichhornia paniculata 50 5.8 4.0 50 66.9 4.8

5 Pontederiaceae Heteranthera dubia 50 88.0 5.8 50 66.9 4.8

6 Pontederiaceae Heteranthera limosa 50 12.0 5.8 50 86.6 6.9

7 Pontederiaceae Heteranthera multiflora 50 2.0 2.0 50 74.0 4.0

8 Pontederiaceae Heteranthera peduncularis 40 0.0 0.0 50 83.0 9.2

9 Pontederiaceae Heteranthera reniformis 50 0.0 0.0 50 66.9 4.8

10 Pontederiaceae Heteranthera zosterfolia 50 28.0 15.0 50 86.6 6.9

11 Pontederiaceae Monochoria vaginalis 50 10.0 6.3 50 66.9 4.8

12 Pontederiaceae Pontederia cordata 50 0.0 0.0 50 80.0 5.5

13 Alismataceae Echinodorus chordifolus 50 0.0 0.0 50 30.0 7.1

14 Alismataceae Sagittaria falcata 50 10.0 7.7 50 78.0 7.3

15 Alismataceae Sagittaria latifolia 50 0.0 0.0 50 80.0 5.5

16 Amaryllidaceae Crinum americanum 50 0.0 0.0 50 96.0 4.0

17 Araceae Colocasia esculenta 50 0.0 0.0 50 83.0 9.2

18 Araceae Colocasia sp. 50 0.0 0.0 50 74.0 4.0

19 Araceae Hydrocotyle umbellata 40 0.0 0.0 40 87.5 0.6

20 Araceae Orontium aquaticum 50 0.0 0.0 50 28.0 13.0

21 Araceae Peltandra virginica 50 0.0 0.0 50 96.0 5.0

22 Araceae Pistia stratiotes 50 0.0 0.0 50 83.0 9.2

23 Azollaceae Azolla caroliniana 50 0.0 0.0 50 83.0 9.2

24 Cannaceae Canna flaccida 50 0.0 0.0 50 86.6 6.9

25 Cruciferae Nasturtium aquaticum 50 0.0 0.0 50 96.0 5.0

26 Eriocaulaceae Eriocaulon compressum 50 0.0 0.0 50 76.0 6.7

27 Haloragaceae Myriophyllum aquaticum 50 0.0 0.0 50 86.6 6.9

28 Haloragaceae Proserpinaca palustris 50 0.0 0.0 50 86.6 6.9

29 Hydrocharitaceae Limnobium spongia 50 0.0 0.0 50 83.0 9.2

30 Iridaceae Iris hexagona 50 0.0 0.0 50 83.0 9.2

31 Lemnaceae Lemna minor 50 0.0 0.0 50 83.0 9.2

32 Marantaceae Thalia geniculata 50 0.0 0.0 50 80.0 5.5

33 Marsileaceae Marsilea quadrifolia 50 0.0 0.0 50 96.0 4.0
C–2

% Large Nymph Survival

Number 

Tested

Test Species Number

Tested

Water 

Hyacinth

Family Genus Species Mean SE Mean SE

34 Menyanthaceae Nymphoides aquatica 50 6.0 6.0 50 83.0 9.2

35 Mimosaceae Neptunia aquatica 50 0.0 0.0 50 96.0 5.0

36 Nymphaeaceae Nuphar luteum 50 0.0 0.0 50 83.0 9.2

37 Nymphaeaceae Nymphaea oderata 50 0.0 0.0 50 78.0 7.3

38 Nymphaeaceae Nymphaea mexicana 50 0.0 0.0 50 83.0 9.2

39 Onagraceae Ludwigia glandulosa 50 0.0 0.0 50 66.9 4.8

40 Onagraceae Ludwigia peploides 50 4.0 2.4 50 86.6 6.9

41 Orchidaceae Dendrobium sp. 50 0.0 0.0 50 83.0 9.2

42 Orchidaceae Vanilla planifolia 50 0.0 0.0 50 74.0 4.0

43 Saururaceae Saururus cernuus 50 0.0 0.0 50 96.0 4.0

44 Scrophulariaceae Bacopa caroliniana 50 0.0 0.0 50 66.9 4.8

45 Scrophulariaceae Bacopa monnieri 50 0.0 0.0 50 66.9 4.8

46 Typhaceae Typha latifolia 50 2.0 2.0 50 86.6 6.9

47 Costaceae Costus woodsonii 50 0.0 0.0 50 76.0 6.7

48 Fabaceae Glycine max 50 0.0 0.0 50 76.0 6.7

49 Graminaceae Oryza sativa 50 0.0 0.0 50 28.0 13.0

50 Musaceae Musa sp. 50 0.0 0.0 50 83.0 9.2

51 Poaceae Saccharum officinarum 50 0.0 0.0 50 74.0 4.0

52 Poaceae Sorghum bicolor 50 0.0 0.0 50 76.0 6.7

53 Poaceae Triticum aestivum 50 0.0 0.0 50 76.0 6.7

54 Poaceae Zea mays 50 0.0 0.0 50 96.0 5.0

55 Solanaceae Lycopersican esculentum 50 0.0 0.0 50 74.0 4.0

56 Zingiberaceae Alpina natans 50 0.0 0.0 50 96.0 5.0

57 Zingiberaceae Curcuma zedoaria 50 0.0 0.0 50 83.0 9.2

58 Zingiberaceae Hedychium coronarium 50 0.0 0.0 50 83.0 9.2

59 Zingiberaceae Renealmia cernua 50 0.0 0.0 50 28.0 13.0

Source: Tipping, et al., 2008.
D–1

Appendix D. Results of the No-choice, Smallnymph Transfer Tests

Ten 1st to 3

rd instars were placed on single test plants in sleeve cages. The tests ended when 

all nymphs developed into adults in the water hyacinth controls and the number of surviving 

life stages were tallied. The percentage of small nymphs that survived was calculated. All 

tests were replicated four times. Shaded rows indicate species where M. scutellaris nymphs 

were able to survive and develop.

% Small Nymph Survival

Test Species Water Hyacinth

Family Genus Species

No. 

Tested Mean SE

No. 

Tested Mean SE

1 Pontederiaceae Eichhornia paniculata 50 22.0 7.3 50 78.0 7.3

2 Pontederiaceae Heteranthera dubia 50 2.0 2.0 50 78.0 7.3

3 Pontederiaceae Heteranthera limosa 50 0.0 0.0 50 34.0 13.2

4 Pontederiaceae Heteranthera peduncularis 50 0.0 0.0 50 34.0 13.2

5 Pontederiaceae Heteranthera reniformis 50 0.0 0.0 50 78.0 7.3

6 Pontederiaceae Heteranthera zosterfolia 50 0.0 0.0 50 34.0 13.2

7 Pontederiaceae Monochoria vaginalis 50 0.0 0.0 50 78.0 7.3

8 Pontederiaceae Pontederia cordata 50 0.0 0.0 50 30.0 7.1

9 Pontederiaceae Pontederia cordata 50 0.0 0.0 50 78.0 7.3

10 Alismataceae Echinodorus chordifolus 50 0.0 0.0 50 30.0 7.1

11 Alismataceae Sagittaria falcata 50 0.0 0.0 50 28.0 8.0

12 Onagraceae Ludwigia peploides 50 0.0 0.0 50 34.0 13.2

13 Typhaceae Typha latifolia 50 0.0 0.0 50 34.0 13.2

Source: Tipping, et al., 2008.
E–1

Appendix E. Response to comment on draft EA

The Arizona Game and Fish Department submitted a comment on draft environmental 

assessment for release of M. scutellaris for biological control of water hyacinth on 

December 16, 2009. Specific issues are indicated in bold text and the response follows. 

The commenter recommends that USDA clearly identify how release sites will be 

chosen and if interagency coordination will occur prior to release, and to describe how 

rapidly the beetle is expected to reproduce and spread to adjacent habitats prior to 

this release and include methods of control once it has been released.

The agent for release is not a beetle but is a planthopper in the insect order Hemiptera. 

Permit applications for environmental release of this organism are submitted to the 

appropriate state department of agriculture for review and comment prior to permit 

issuance.

Monitoring of M. scutellaris will be conducted by researchers at the USDA-ARS Invasive 

Plant Research Laboratory. Four long term sites currently serving as ecological study sites 

in Florida will become the first release and evaluation sites for M. scutellaris. 

Establishment and rates of spread in the field will be determined. 

Undesired effects of M. scutellaris are not predicted, so mitigation of local populations is 

not expected. However, the planthopper’s narrow host range suggests that locally 

undesirable effects could be mitigated by using herbicides to eliminate water hyacinth 

infestations on which the insect resides.

The commenter has suggested that USDA develop a strategy to identify where 

“tamarisk” will be suppressed but native vegetation may not reestablish naturally due 

to altered hydrology. Also, the commenter has indicated that USDA develop a 

vegetation monitoring protocol to determine the response on the riparian plant 

community and to document evidence of native tree recruitment and survival.

Water hyacinth is an aquatic plant and its removal would not require subsequent riparian 

plant restoration projects. Removal of water hyacinth is not expected to have an impact on 

native tree recruitment and survival. 

The commenter raises general concerns regarding unexpected effects of biological 

control agents, and in particular, the potential for host shifting.

Host shifts by introduced weed biological control agents to unrelated plants are rare 

(Pemberton, 2000). 
E–2

The commenter uses the tamarisk leaf beetle as an example of a biological control agent 

that has exhibited unexpected behavior. However, the commenter is not completely correct

in his statements regarding releases of the beetle. As for releases of vertebrate species as 

biological control agents, it is well known that this has often resulted in adverse 

environmental consequences. This practice is discouraged (Howarth, 1991) and APHIS 

does not approve it. 

The commenter indicates that water hyacinth does not currently occur in Arizona, and 

that two sites where it has occurred have been eradicated since July of 2000. 

Because M. scutellaris does not currently occur in Arizona, it would not likely be released 

in that State and would not likely spread there because its host (water hyacinth) does not 

occur there.

The commenter requests that an independent scientific review be completed 

concerning the ecology and behavior of this insect.

An independent review has occurred. The Technical Advisory Group for the Biological 

Control Agents of Weeds (TAG) recommended the release of M. scutellaris on February 2, 

2009. The TAG is an independent interagency group of scientists and regulatory specialists 

that reviews the research petition submitted by the biological control researcher and 

provides a recommendation to APHIS. TAG members that reviewed the release petition 

(Tipping et al., 2008) included representatives from the Bureau of Indian Affairs, 

Cooperative State Research, Education, and Extension Service, U.S. Geological Survey, 

Environmental Protection Agency, California Department of Food and Agriculture, U.S. 

Army Corps of Engineers, Bureau of Reclamation, U.S. Forest Service, and Agriculture and 

Agri-Food Canada, Health Canada. 
E–3

The commenter suggests that there is inherent risk in the use of biological control 

agents, and that home range testing and screening may not adequately address the 

ability of a biological control agent to use and cause considerable population level 

damage to non-target species.

The risk analysis provided by quarantine host range testing indicated that there would be no 

risk to non-target species. In contrast to the reviewer’s comment, quarantine host range 

testing has repeatedly been shown to be highly predictive of the eventual environmental 

host range of biological control agents following release. The host specificity screening 

process used for biological control agents of weeds is inherently conservative which 

contributes to the good safety record of recent weed biological control introductions 

(Messing and Wright, 2006).

The commenter states that the EA fails to show that M. scutellaris could not persist on 

and affect native species in the genus Heteranthera and members of the 

Pontederiaceae.

The data are clear that M. scutellaris cannot sustain itself on Heteranthera species (Tipping 

et al., 2008). In all of the testing, only a single nymph of M. scutellaris was able to survive 

on H. dubia after 21 days, and this single nymph was never able to develop into an adult. 

Although insects can lay eggs on many plants, this is not evidence of utilization or future 

damage. For example, many lepidopteran species will freely lay eggs on cages or nontarget plants that do not support growth and development by immatures. In host specificity 

testing, M. scutellaris failed to survive on all the non-target plant species, including all 

Heteranthera species. 

The commenter indicated that the experiments were not thorough because only four

repetitions using two females and one male were conducted.

The number of replications in any experimental design should be guided in large part by the 

amount of variation that is present. As a result of low variability, we believe four 

replications were appropriate as a part of the experimental design. Some studies were 

replicated five times as a response to increased variability. 

Using only two females in the test minimized intraspecific competitive interactions which 

may have confounded the interpretation of the results. For example, adding too many 

females actually reduces oviposition, a condition that might underestimate the insect’s host 

range. 
E–4

The commenter states that Heteranthera species are used for cover, oviposition, and 

feeding sites, by certain frogs and salamanders, and that the EA did not address 

potential effects to these species from host shifting by M. scutellaris.

Many insect herbivores (including M. scutellaris) can survive on relatively few plant 

species, most of which are close relatives. These relationships between insect herbivores 

and their host plants have coevolved over millennia, resulting in insect herbivore diets that 

are as stable as they are predictable. Because it has been shown quantitatively that M. 

scutellaris will not develop on Heteranthera species in host specificity testing (Tipping et 

al., 2008) there is no reason to discuss potential impacts on amphibian and reptile species

that may utilize Heteranthera species. 

Control of water hyacinth is expected to benefit organisms in fresh water ecosystems and is 

not expected to negatively impact non-target organisms. No endangered or threatened 

organisms are dependent on water hyacinth. Large infestations of water hyacinth in small 

ponds have been implicated in causing declines in phytoplankton abundance (McVea and 

Boyd, 1975), which likely impacts zooplankton densities and diversity (Schmitz et al.,

1993). Reduced plankton abundance and dissolved oxygen levels under modest water 

hyacinth infestations (10-25% cover) caused declines in fish productivity in experimental 

ponds (McVea and Boyd, 1975). Further, depleted oxygen levels under water hyacinth 

mats have been implicated in fish kills (Timmer and Weldon, 1967). Also, Griffen (1989) 

partially attributed declines in the federally endangered kite (Rostrhamus sociabilis) to 

destruction of kite habitat by water hyacinth. Thus, reductions in water hyacinth 

infestations would likely benefit a variety of native fauna. 

References:

Griffen, J. 1989. The Everglades kite. Aquatics 11(3):17–19.

Howarth, F.G. 1991. Environmental impacts of classical biological control. Annual 

Review Entomology. 36:485–509.

McVea, C. and C.E. Boyd. 1975. Effects of waterhyacinth cover on water chemistry, 

phytoplankton, and fish in ponds. Journal of Environmental Quality 4(3): 375–378.

Messing, R.H. and M.G. Wright. 2006. Biological control of invasive species: solution or 

pollution? Front. Ecol. Environ. 4: 132–140.

Pemberton, R.W., 2000. Predictable risk to native plants in weed biological control. 

Oecologia, 125:489–494.

Schmitz, D.C., J.D. Schardt, A.J. Leslie, F.A. Dray Jr., J.A. Osborne, and B.V. Nelson. 

1993. The ecological impact and management history of three invasive alien aquatic plant 

species in Florida, pp.173–194. In: McKnight, B.N. Biological Pollution: The control and 
E–5

impact of invasive exotic species. Indiana Academy of Sciences, Indianapolis, Indiana.

Timmer, C.E. and L.W. Weldon. 1967. Evapotranspiration and pollution of water by 

waterhyacinth. Hyacinth Control Journal. 6:34–37.

Tipping, P.W., Center, T.D., and Dray, Jr., F.A., 2008. Proposed field release of 

Megamelus scutellaris Berg (Hemiptera: Delphacidae) for control of water hyacinth 

Eichhornia crassipes Mart. (Solms) (Pontederiales: Pontederiaceae). Petition submitted to 

the Technical Advisory Group for Biological Control Agents of Weeds. 34 pp.