The Q&A Archives: Cucumber Beetles

Question: In '97 I got a lot of yellow/black striped beetles on my winter squash vines. I sprayed them with bug spray meant for roses because that was all I had, which seemed to work but I had to do this weekly. The bugs also spread to my pole beans....What are they and how can I keep them at bay next season?

Answer: First let me suggest rather STRONGLY that you do NOT use your rose spray on vegetables. These insecticides may be toxic when ingested. You should NOT be eating them! Only use insecticides that are specifically formulated for edible plants.<br><br>It sounds like you may have an infestation of cucumber beetles, which are yellowish green, with black spots or stripes. Larvae feed on the roots, they pupate, finally becoming beetles, which then chew the plant parts and are most destructive as well as visible. These adults overwinter in debris in your garden.<br><br>Now, how to control them. Since the adults overwinter in garden debris and lay the eggs in the spring when the soil warms up, your "modus operandi" should be to clean up that debris thoroughly. It's best to do this in the fall, to remove overwintering sites, but at the very least, do this FIRST thing in the spring when you get out into your garden. Do NOT put the debris in your compost! <br><br>Next, never plant those squash or beans in the same place. You need to rotate these crops. <br><br>Try covering your plants from germination until bloom time with floating row covers secured all around so the adults can't fly in. (You'll need to check periodically to be sure you haven't trapped any beetles underneath.) Remove the cover when the plants flower, so the bees can pollinate them. By then, the plants should be large enough to withstand some feeding by the beetles. Also, a thick straw mulch around plants can deter beetles from laying their eggs there. <br><br>If you find yourself with an infestation of adult beetles, use a pyrethrum-based spray. Use this sparingly, since it can harm beneficial and pollinating insects.

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