United States 

Department of 

Agriculture

Forest 

Service 

Intermountain 

Region 

Forest Health Protection 

Boise Field Office 

1249 South Vinnell Way, Suite 200 

Boise, ID 83709-1663

 Caring for the Land and Serving People Printed on Recycled Paper 

File Code: 3420 Date: March 30, 2005 

Route To: 

Subject: FHP Report BFO-PR-05-02 

To: Forest Supervisor, Sawtooth NF 

 

 

Enclosed is Forest Health Protection project report, BFO-PR-05-02. This report evaluated the 

biological control agent, Aphthona flea beetles, population establishment, and impacts to leafy 

spurge west of Featherville, ID along the South Fork Boise River. The objective of the 

biological control agent monitoring was to determine the establishment of Aphthona from the 

1996 Forest Health releases and from 1998 and 1999 helicopter releases, in addition to document 

the impacts to the leafy spurge population from the Aphthona beetles. This was an initial effort 

to prepare for a more complete survey of the area to measure the success rate of the helicopter 

drops of Aphthona beetles. 

If you have any questions, please contact Carl Jorgensen at 208-373-4225 or Dayle Bennett at 

208-373-4227 in the Forest Health Protection Boise Field Office. 

For FHP evaluations, project reports, and trip reports on this or other topics, visit our Web site at: 

http://fsweb.r4.fs.fed.us/unit/spf/tripreports/bk_beetle.shtml. For more general information on 

FHP programs and services visit our combined Regions 1 and 4 Web site at: 

http://www.fs.fed.us/r1-r4/spf/fhp/ or visit our national FHP Web site at: 

http://www.fs.fed.us/foresthealth/. 

/s/ Dayle D. Bennett (for) 

WILLIAM W. BOETTCHER 

Director, State and Private Forestry 

 

Enclosure 

cc: Warren Ririe, Dayle D Bennett, Carl L Jorgensen, Dwight Scarbrough, Joy C Roberts, John 

Shelly, George Markin, Thomas N Barbouletos 

CJorgensen:al 
Monitoring Aphthona Species for Population Establishment and Impacts to Leafy Spurge in the 

Shake Creek Area from Helicopter and Ground Releases 

Report: BFO-PR-05-02 

Prepared by: 

Carl Jorgensen 

Entomologist 

Boise Field Office 

March 21, 2005 

Forest Health Protection 

Intermountain Region 

1249 Vinnell Way, Suite 200 

Boise, ID 83709 
Introduction 

In 1996, Forest Health Protection staff released Aphthona nigriscutus at several sites along the 

South Fork Boise River drainage to manage a growing leafy spurge population. In 1998 and 

1999, the Fairfield Ranger District began using helicopters to distribute Aphthona beetles for 

leafy spurge in the area. Those releases were documented using GPS points. In later years, the 

helicopter releases continued but were not GPS'ed. The helicopter drops have the advantage of 

distributing the Aphthona quickly to many of the leafy spurge infestations that are not easily 

accessible from the ground. These sites have not been monitored since the release date. The 

objective of the biological control agent monitoring was to determine the establishment of 

Aphthona from the 1996 Forest Health releases and from 1998 and 1999 helicopter releases. 

This was an initial effort to prepare for a more complete survey of the area to measure the 

success rate of the helicopter drops of Aphthona beetles. During 1999 and 2000, Oberea 

erythrocephala was also released in the area and was noted when found. 

Methods 

Monitoring of the release sites was conducted June 29-30, 2004, when the adult Aphthona

beetles were actively feeding on leafy spurge. Release sites were located using a GeoExplorer 3 

GPS unit and maps of the release sites, as recorded in information documented by Andrew 

Deutscher*. 

At each surveyed release site, monitoring crews first conducted a 5-minute visual search for 

biological control agents. After the 5-minute visual survey, the site was surveyed using a sweep 

net. If less than 10 biological control agents were found during the 5-minute visual survey, then 

four areas selected at random within 5 meters from the release site were swept using a sweep net. 

The sweeping procedure involved making four sweeps and then checking contents for Aphthona

beetles. The number of insects were tallied and recorded for the 5-minute visual survey and the 

four-area sweep. 

Once established, a population of the Aphthona beetles begins to impact leafy spurge plant 

density and height. This impact is often referred to as the "bomb-blast" effect where the beetles 

have killed or stunted the leafy spurge plants (Figure 1). Typically, the initial bomb-blast effect 

is about 1 meter in diameter. The size of the affected area expands outwardly each year as the 

population of beetles increases. When present, the bomb-blast area at each monitoring site was 

measured to the nearest meter cross-slope and perpendicular to the cross-slope measurement at 

the widest spot. The end points for measurement occurred at the transition area between 

stunted/dead stems and the unaffected live stems of leafy spurge. If there was a bomb-blast 

effect, the transition zone between the dead/stunted and unaffected live leafy spurge stems was 

swept. The number of insects were tallied and recorded for the 5-minute visual survey and the 

four-area sweep. 

*Andrew Deutsher was a temporary Forest Service employee who coordinated the Aphthona releases in 1998-2000. 
Figure 1. Picture of "bomb-blast" effect in leafy spurge patch following an Aphthona flea beetle release 

(USDA Forest Service photo). 

The Aphthona populations at the helicopter release sites and the Forest Health Protection release 

sites were evaluated and recorded into one of the following categories: 

 1. "None" was recorded when no Aphthona or damage by Apthona on leafy spurge was 

found. 

 2. "Present" was recorded when one or two Apthona were found, or minimal damage to 

leafy spurge was found even in the absence of the beetles. 

 3. "Established" was recorded when a small population of breeding adults, typically less 

than 50 individuals was found at the site and the bomb-blast effect on the leafy spurge was 

barely noticeable, i.e., less than 2 meters. 

 4. "Marginally collectable" was recorded when a healthy population of breeding Aphthona

adults, typically about a 100 individuals was found at the site and the bomb-blast effect was 

greater than 2, but less than 10, meters in diameter. 

 5. "Collectable" population was recorded when hundreds of Aphthona beetles were found 

at the site and the bomb-blast effect had reached a diameter greater than 10 meters. 
Results and Discussion 

A total of 15 release sites were monitored (Figure 2). Aphthona beetles were found at seven of 

the monitored sites. Four sites were classified as "marginally collectable" populations. At three 

sites, Aphthona populations were classified as "present" level. Minimal or no impacts to the 

leafy spurge were noted, but adults were found at these three sites. At eight of the monitored 

sites, no Aphthona or insect damage was found. 

The four sites that had "marginally collectable" populations were Little Water 1, Little Water 3, 

Big Water 3, and Bird Creek 1. The size of the bomb-blast at each of these sites, except Big 

Water 3, was about 10 meters in diameter. The Big Water 3 site had a bomb blast that measured 

45 x 15 meters, but this may be an over estimation due to the influence of trees and shrubs near 

the site. Big Water 3 also had a significant amount of cheatgrass (Bromus tectorum) associated 

with the site. Regardless of the influence of other factors, these four sites should have sufficient 

populations of Aphthona from which collections can be made and redistributed to other leafy 

spurge infestations in 2005. 

One Oberea erythrocephala was noted in the Little Water drainage, away from the monitored 

release sites. Several Oberea were found during the collection/redistribution day near the elk 

shed in the Big Creek drainage on June 29, 2004. Further monitoring of the area will likely find 

an established population of Oberea in the area between Big Water Creek and Little Water 

Creek. These insects are quite mobile and will likely disperse without human involvement. 

Recommendations 

In my estimation, all the release sites near the elk shed should be used to redistribute as many 

Aphthona beetles as possible to leafy spurge infestations in other drainages. Additionally, I 

recommend, a collection field day in this area where land managers from other Districts, Forests, 

and agencies can come to collect Apthona beetles for releases on their leafy spurge infestations. 

Releases that are easily accessible should be monitored annually or biennially to determine if the 

Apthona population is at collectable levels for redistribution increasing the number of accessible 

Apthona nursery sites in southern Idaho. 

The Little Water drainage has at least two populations of collectable Aphthona, Little Water 1 

and Little Water 3. These sites could be used to release more insects in the Little Water drainage 

without going back to the elk shed area for biological control agents. The Bird Creek 1 site 

should also have a population of biological control agents that could be redistributed into that 

immediate area. 

It appears not all of the helicopter releases were successful in establishing populations. 

However, some have definitely established and have bomb blast areas greater than 10-meters in 

diameter. These sites should be noticeable from a low flying helicopter and do not need to 

receive additional releases. Instead, helicopter releases made this coming summer should be 

directed at leafy spurge infestations which show no obvious bomb-blast effects from the 

Aphthona beetles. 
John Shelly and his staff have done an excellent job redistributing these insects in the drainages 

around the elk shed. After several years of releasing biological control agents, the benefits are 

beginning to have noticeable impacts on the leafy spurge population at many of the release sites. 

Carl Jorgensen 

Entomologist 

Forest Health Protection 
MARSH2

CORR

CO

MARSH 1 98

BIG WATER 3

BIRD CREEK 1

MARSH 5 1999

MARSH 4 1999

LITTLE WATER 3

LITTLE WA

Population Level

PRESENTNONEMARGINALLY COLLECTABLE

1:40,000 {

Figure 2. Population level and location of monitored Aphthona nigriscutis release sites during June 28-30, 2004

3 overlap on the Map) 
Appendix 1. Summary Table of Monitoring for Aphthona nigriscutis at the release sites, June 28-30, 2004 

 AIR_TEMP Percent of Weed Stage Weed Patch No. of

SITE_NAME WEATHER (Fahrenheit) WIND Seed Bolt Bud

Flowe

r (Acres) Population Level Agents

MARSH 1 1998 CLEAR <60 LIGHT 0 0 30 70 1-10 NONE 0 

MARSH 2 1998 CLEAR 71-80 LIGHT 0 0 20 80 1-10 NONE 0 

MARSH 4 1998 

PARTLY 

CLOUDY 71-80 CALM 0 20 20 60 1-10 NONE 0 

MARSH 3 1999 CLEAR 71-80 CALM 0 0 30 70 1-10 NONE 0 

MARSH 4 1999 

PARTLY 

CLOUDY 80-90 CALM 0 10 40 50 1-10 PRESENT 10 

UNKNOWN 

MARSH 

PARTLY 

CLOUDY 71-80 LIGHT 0 30 20 50 1-10 PRESENT 1 

MARSH 5 1999 CLEAR 80-90 CALM 0 20 30 50 0.25-1 PRESENT 11 

BIRD CREEK 2 

PARTLY 

CLOUDY 71-80 LIGHT 0 0 50 70 1-10 NONE 0 

CORRAL1 CLEAR 71-80 LIGHT 0 20 20 60 0.25-1 NONE 0 

CORRAL 2 CLEAR 71-80 LIGHT 0 30 30 40 1-10 NONE 0 

CORRAL3 CLEAR 71-80 CALM 0 30 30 60 1-10 NONE 0 

LITTLE WATER 1 

PARTLY 

CLOUDY 71-80 LIGHT 0 20 20 60 >10 MARG COLLECTABLE 1 

LITTLE WATER 3 

PARTLY 

CLOUDY 71-80 CALM 0 30 30 40 >10 MARG COLLECTABLE 1 

BIG WATER 3 

PARTLY 

CLOUDY 80-90 LIGHT 0 20 30 50 1-10 MARG COLLECTABLE 0 

BIRD CREEK 1 

PARTLY 

CLOUDY 61-70 LIGHT 10 10 20 60 1-10 MARG COLLECTABLE 124 

 

Appendix 1. Continued 

 Weed Canopy Percent Canopy Cover 

Releas

e 

SITE_NAME Height (cm) Weed Tree 

Shru

b 

For

b 

Gras

s Litter Bare Ground COMMENTS Year 

MARSH 1 1998 40 40 0 20 20 10 5 5 NEW RELEASE NEEDED 1998 

MARSH 2 1998 40 20 0 30 20 15 10 5 NO INSECTS 1998 

MARSH 4 1998 41 40 10 20 10 20 0 0 SOME DAMAGE PRESENT 1998 

MARSH 3 1999 40 30 10 20 20 10 5 5 NOT MUCH DAMAGE 1999 

MARSH 4 1999 45 30 10 20 25 10 5 0 DAMAGE PRESENT 1999 

UNKNOWN 

MARSH 31 20 40 30 10 0 0 0 POSSIBLE RELEASE ? 

MARSH 5 1999 21 30 15 15 10 20 10 0 1999 

BIRD CREEK 2 40 30 15 10 15 10 15 5 1996 

CORRAL 1 30 40 0 20 10 20 5 5 NO INSECT DAMAGE 1999 

CORRAL 2 35 80 5 5 0 5 0 0 NO APATHONA PRESENT 1999 

CORRAL 3 40 70 10 5 5 10 0 0 1999 

LITTLE WATER 1 43 40 5 10 0 40 5 5 BOMB BLAST 15x12 M 1996 

LITTLE WATER 3 35 60 10 10 0 10 5 5 BOMB BLAST 14x 8 M 1996 

BIG WATER 3 40 60 10 10 5 0 10 5 BOMB BLAST 45 x 15 M 1996 

BIRD CREEK 1 50 60 5 5 5 10 5 5 

NOT SURE WHERE DROP 

WAS 1996