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Extension > Local Extension Offices > Clay > Garden > Articles > Colorado potato beetle

Colorado potato beetle

Colorado potato beetle adult. Photo: UMN Dept. Entomology

Gardeners growing potato, eggplant, pepper or tomato may be observing Colorado potato beetle on their plants. Adults are oval in shape and 3/8 inch long and have 10 narrow black stripes on their wing covers. Yellowish orange oval eggs, laid in clusters, may be found on the underside of leaves. Young larvae are brick red with black heads while older larvae are pink to salmon colored with black heads. All larvae have two rows of dark spots on each side of their bodies. Both larvae and adults feed on plant foliage. If left untreated, they can completely defoliate plants leading to reduced yields. Colorado potato beetle has one to two generations a year and is seen from spring until harvest.

Several options exist for managing Colorado potato beetle. Handpicking is an option in small gardens. Handpicking takes time and patience and needs to be repeated as eggs hatch. Spinosad is a low impact insecticide that is effective against Colorado potato beetle. Most importantly, there is no known resistance by these beetles to this insecticide. 

Traditional insecticides such as carbaryl and permethrin are generally not effective as most populations of Colorado potato beetle have developed resistance to them. It is possible that some relatively newer pyrethroids, such as lambda cyhalothrin or cyfluthrin can help to manage these beetles. However, if sprays do not seem to be affecting them, discontinue their use and switch to another management method. Source: Jeffrey Hahn, Extension Entomologist.

Contacts

Randy Nelson
Extension Educator, Home Hort & Ag Production Systems
(218) 299-5020
nels1657@umn.edu
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