Colorado potato bugs, also know as Colorado potato beetles, were first observed feeding on potatoes in Colorado in 1859, and quickly spread across the U.S. They are now found in every state and are a major pest for both home gardeners and commercial agriculture. Most pesticides available to the home gardener are ineffective against potato bugs, so careful monitoring and organic gardening strategies are critical to controlling them.
Potato Bug Identification
Adult potato bugs are 3/8 inch long with an orange head and a yellow body with black stripes. They overwinter in the soil and emerge in late spring, around the same time potato vegetation appears. They lay clusters of small, orange eggs on the undersides of leaves. Young larvae are deep red with black heads; older larvae are pink to salmon with black heads. All larvae have black spots on the sides of their bodies. In warm weather, larvae may mature in as little as 10 days. In regions with long, hot summers, potato bugs may have two or more generations each year.
Damage from Potato Bugs
Potato bugs feed on the leaves and stems of potato plants, and in large numbers, can completely defoliate the plant. Potato plants can usually withstand infestations early in the season, but damage is severe if it occurs when the potato tubers are actively growing, usually right after blooming.
Potato bugs also feed on any plant related to potatoes, including peppers, tomatoes and eggplants.
Potato Bug Prevention
Tilling the soil in late fall or early spring can kill overwintering potato bugs, reducing their numbers. Crop rotation is largely ineffective because potato bugs can fly for many miles. Try growing potatoes every other year to reduce potato bug populations. Remove all plant debris in the fall, and choose early-maturing potatoes that are ready for harvest in 80 days or less. These varieties will mature before adult potato bugs are actively feeding. Plant potatoes as soon as the soil can be worked in the spring.
Control of Potato Bugs
Handpick potato bugs, as well as their larvae and eggs, and drop them in a bucket of soapy water to destroy them. In larger gardens, where handpicking is not practical, spray the potato plants with Bacillus thuringiensis. This naturally occurring soil bacterium paralyzes the gut of potato bugs, slowly starving them. Read package labeling, though, and buy Bt labeled specifically for use on potato bugs, since many products work only on moth larvae.
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