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Connecticut Garden Journal: Spud Menace, The Potato Beetle

Jul 6, 2017

This pest is native to the Southwest United States but has spread and become a worldwide problem for anyone growing potatoes. It's the Colorado potato beetle. 

The Colorado potato beetle is so prevalent it's often just called the potato bug. Unlike smaller insects that are hard to see, the potato beetle is obvious. The large, black and yellow striped beetle is found on potato leaves laying clusters of orange eggs on the undersides of the leaves. The eggs hatch into a red, soft larvae that feeds heavily, defoliating plants. Although potatoes can lose a third of their leaves and still produce a crop, the potato beetles can devastate plants.

To control the beetle you have to understand its lifecycle. Potato beetles overwinter just below the soil line. In spring the adults can't fly, but walk to the emerging potato shoots. Mulching with a two to four inch thick layer of straw at potato planting time will thwart these adults from finding the new potato plants.

Hand pick the adults in spring as you see them, and drop them into a pail of soapy water. Check the undersides of the leaves every few days and crush the orange egg clusters. Don't forget to check eggplant and other tomato family crops, too.

If the potato beetles have gotten out of control, spray Neem oil or a form of Bt called potato beeter on the plants. These organic controls work best on the young larvae so spray early. In the future rotate crops, plant resistant varieties, such as King Harry, or grow early maturing varieties that mature before the beetles population swells in late summer.

Next week on the Connecticut Garden Journal, I'll be talking about summer flowering shrubs. Until then, I'll be seeing you in the garden.