Brachypterolus pulcarius 
<<back to yellow toadflax
Common Name
Toadflax flower-feeding beetle
Weeds Impacted
This beetle attacks both yellow and Dalmatian toadflax, although it appears to have a far greater impact on yellow toadflax. Larvae feed on reproductive structures within the flowers, including maturing seeds, and can reduce yellow toadflax seed production by up to 90%. Adult feeding on young stems decreases overall plant health by causing increased branching and stunted growth.
Insect Description
Adults are small, black, oval beetles approximately 2 mm (about 1/16 in) long.
Life Cycle
Adults emerge from the soil in May and are active until mid-summer. Females lay eggs in the toadflax flowers, and larvae hatch out to feed on pollen, ovaries, and developing seeds. Mature larvae then enter the soil to pupate. Winter is spent in the pupal stage.
Field Identification
If multiple insect agents are present on toadflax, B. pulicarius will be the only beetle that is not a weevil. Its shiny, black, oval appearance makes it clearly recognizable and easily distinguished from both Mecinus janthinus and any of the Rhinusa (formerly Gymnetron) species, all of which have a more elongate and typical “snout beetle” form.
Availability
B. pulicarius is readily available in Washington, Oregon, Idaho, and throughout the intermountain west. Adults can be collected wherever yellow toadflax is found, usually from May to about mid-July; however, the beetle is likely already present at most yellow toadflax sites. To inquire about availability and to request this biocontrol agent, please download, complete and submit this form.
Comments
Prospects for the use of B. pulicarius as a long-term, effective agent for control of Dalmatian toadflax are currently unclear. It is hoped that a Dalmatian toadflax-adapted strain of the beetle will eventually have similar impacts to those found on yellow toadflax.
Using the Agent: Integrated Weed Management (IWM)
Because B. pulicarius is already found in most yellow toadflax infestations, redistribution may be unnecessary. Using B. pulicarius with the seed-feeding weevil Rhinusa antirrhini can increase the impact on seed production.
Agents should only be released at sites where toadflax infestations are large and immediate eradication of the weed is not the primary objective. Smaller populations of toadflax can be either hand-pulled or sprayed, but treatments must be repeated annually for up to 5 or 6 years. Viable root fragments can remain after pulling, and herbicides will not immediately kill or penetrate all plants. If spraying larger infestations, herbicides should be applied only after insect agents have definitively established. Consult with your county weed office, Extension office or an IWM practitioner to determine which herbicide treatments are safe and appropriate.
Burning is not recommended, as it increases the susceptibility of a site to further infestation. Plowing or disking can eliminate toadflax in cropland if repeated regularly. Mowing will not control toadflax and can work against any potential agent impacts when the insects are active. Plants should be mowed only if necessary either before May or in the fall when insects are not feeding or developing on the plants.
Any management of toadflax should involve revegetation with native or other desirable plants. Revegetation promotes competition between plants, which stresses weeds and allows for more effective treatment. To learn more about revegetation and IWM, click here.
References
Coombs, E. M., J. K. Clark, G. L. Piper, and A. F. Cofrancesco, Jr. 2004. Biological Control of Noxious Weeds in the United States. Western Society of Weed Science, Oregon State Univ. Press, Corvallis.
Wilson, L. M., S. E. Sing, G. L. Piper, R. W. Hansen, R. De Clerk-Floate, D. K. MacKinnon, and C. Randall. 2005. Biology and Biological Control of Dalmatian and Yellow Toadflax. USDA Forest Service. FTET-05-13.
Photo Credits
Brachypterolus pulicarius adult - D. K. MacKinnon, Colorado State University, bugwood.org (insectimages.org), http://www.insectimages.org/images/768x512/1416023.jpg
Brachypterolus pulicarius adults - Bob Richard, USDA-APHIS-PPQ, bugwood.org (insectimages.org), http://www.insectimages.org/images/768x512/1416025.jpg
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