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Colorado Potato Beetles

Likely the most damaging of insects in relation to potatoes, the Colorado potato potato beetle can, if left untreated, completely defoliate plants.  Up to 75% of the damage caused is by older larvae during feeding.  Eggs are laid on the underside of leaves in clusters of 10-30 eggs at a time.  Females can lay a few hundred in their several week lifespan.  Depending on temperature, eggs typically begin to hatch in approximately 2 weeks.  First instar larvae are brick red with black heads whereas fourth instar larvae tend to be a pink or salmon in color with a black head.  Maturation can take as little as 10 days or as long as approximately one month to occur depending on the consistency of temperature during development.  Aside from potatoes, both larvae and adults will also feed on eggplant, tomato and other plants in the nightshade family.  Pupation occurs in the soil and adults typically emerge by midsummer.  Colorado Potato Beetles over winter as eggs which hatch around May, when potato growth is active.  Adult Colorado Potato Beetles are 3/8” in length with ten narrow black stripes over their yellow base color.  Due to insecticidal resistance, gardeners may need to utilize multiple methods of control during the growing season.  Growing potatoes every other year may aide in lessening populations.  Hand picking the Colorado Potato Beetles and their larvae and then promptly dropping them into a bucket of soapy water may be useful for small gardens.  Other means of control include microbial and biological.  Lady beetles feed on Colorado potato beetle eggs and may be released early in the season depending on weather in order to consume eggs that have overwintered. Historically, these potato beetles infested buffalo bur; however, with the settlers came potatoes, at which time the potato beetles spread eastwards out of Colorado following the potato crops at a rate of approximately 85 miles per day.  During warmer weather (exceeding 75 degrees), adult Colorado Potato Beetles are known to fly nearly 3 miles; therefore, movement from crop to crop can be rapid.