This article was published originally on 6/9/2010
Recent phone calls indicate home gardeners are being frustrated (again!) by the Colorado potato beetle. See the photos below. For more on this native insect-turned-pest, see Horticulture and Home Pest News, June 4, 2008.
The list of insecticides for homeowners is not much different now than it was two years ago. The first-choice products are the synthetic pyrethroids such as permethrin, cyfluthrin and esfenvalerate. Look for products labeled for use on potatoes in the home garden and apply according to label directions, including spray early, spray often.
Repeated and intensive use of insecticides against the Colorado potato beetle has lead to resistant to nearly all insecticides, including the common garden insecticide Sevin (carbaryl) in many areas. Alternate chemical classes to delay resistance development. Spray insecticide from one class during May and June for the first generation and then switch a different class during July and August for the second generation. Remember that the biorationals such as spinosad are only effective against very young larvae; they will not kill large larvae or adults.
Colorado potato beetle (adult).
Colorado Potato Beelte Larva.