these little yellow with black stripes beetles are killing my zucchini and pumpkins. Please help with suggestion to control. Right now I’m hand picking. Thank you.
Thank you for contacting the Toronto Master Gardeners. Your beetles are called cucumber beetles, and they are a common pest for the cucurbits family (cucumbers, squash including zucchini, pumpkins, watermelons, melons and gourds). There are two types of cucumber beetles : yellow with black stripes like yours, and yellow with black spots. They can cause a lot of damage, both as adults when they feed on leaves, stems, flowers and fruits, and as larvae when they feed on roots. But the biggest problem with cucumber beetles is that they carry a disease called bacterial wilt from plant to plant, and this disease is fatal, with no way to treat it.
The adults overwinter in the soil, under leaves and bark and on weeds. They emerge in early summer and start feeding on seedlings and young plants. Then they mate and lay eggs on the soil near the base of plants. The larvae emerge and feed on roots, and then new adults emerge in mid summer, and the cycle starts again.
The best (easiest) way to manage cucumber beetles is to prevent them rather than suppress them once you have them. Since you already have them, here are some things that you can do to get rid of them. Handpicking them as you are doing in the morning or evening and dropping them into a bucket of soapy water, or using a portable hand vacuum to scoop them up are probably the most effective ways to deal with them. You can also try insecticidal soap, or use yellow sticky traps (available in garden centres or home and garden stores) or pheromone lures (order these online).
There are many things you can do to prevent cucumber beetles from feasting on your plants. These include planting in a different spot so that you avoid planting again in a particular spot for 2-3 years (because the adults overwinter in the soil near the plant, and these insects carry bacterial wilt), planting cultivars that are resistant to cucumber beetles and to bacterial wilt, using floating row covers over seedlings until the flowers begin to bloom and they are ready for pollination, delaying your planting time to avoid cucumber beetles when they first become active in the early summer, and covering your soil with a thick mulch since cucumber beetles like to lay their eggs on bare soil.
Here are some links that provide further information :
Missouri Botanical Garden – Cucumber beetles
Laidback Gardener – Learning to Deal with Cucumber Beetles
Missouri Botanical Garden – Bacterial Wilt of Cucumber
Controlling cucumber beetles can be challenging. Good luck with your plants !
July 25, 2021