Learn to Identify and Prevent Cucumber Beetles
How to Identify Cucumber Beetles
Adult striped cucumber beetles are about ¼ inches long and have a yellow-and-black striped abdomen and a dark-colored head and antennae. Spotted cucumber beetles are the same length but have 12 black spots on a yellow abdomen. The larvae are worm-like, white, dark-headed, and have three pairs of legs on the thorax.
Identifying Cucumber Beetle Damage
While cucumber beetle larvae feed on cucurbit roots, adult feeding is more damaging to the crop. Adults feed on leaves and can stunt plant growth. Look for holes and yellowing and wilting leaves.
Feeding on flowers can reduce fruit production, and direct feeding on fruits causes unattractive scars and pock marks on the fruit, too.
Often, the cucumber beetles alone will not kill the plants or cause major damage, but the spread of disease will. Feeding by adult cucumber beetles can spread bacterial wilt disease among cucurbit plants, even when the population density of the insect is low.
Adult cucumber beetles overwinter in weeds, garden debris, and woody areas. The diseases they carry can also overwinter internally, and can be passed onto plants the next spring through fecal matter.
How to Get Rid of Cucumber Beetles
- Inspect newly planted cucurbit plants for the presence of this beetle; be watchful when plants are seedlings.
- Use yellow sticky traps to catch cucumber beetles and other pests.
- Knock beetles to the ground and catch them with a piece of cardboard placed under the plant. Or, use a handheld vacuum to suck up the beetles. They are very hard to hand-pick, but it is easier to hand-pick them with yellow gloves coated in petroleum jelly.
- Cover seedlings with row covers, though you must remove them during blossoming time several hours each day to allow for pollination.
- Few insecticides can be used on cucurbit plants because they are very sensitive. They would need to be used when plants are just beginning to emerge through the soil. Please contact your local cooperative extension for a list of approved insecticides for your area.
- Folk advice from The 1963 Old Farmer’s ÃÛÌÒÁµÈË states that nasturtiums and wood ashes are effective against cucumber beetles.
How to Prevent Cucumber Beetles
- If you till your garden in the late fall, you will expose cucumber beetles hiding there to harsh winter conditions and reduce their populations next year. Remove all debris after fall harvest to reduce overwintering habitat.
- Rotate crops so cucurbit crops are not planted directly into soils containing overwintering populations.
- Transplanting young plants rather than direct seeding can protect vulnerable seedlings from damage.
- Planting trap crops (cucurbit varieties highly attractive to cucumber beetles) at the perimeter of the harvested crop can keep cucumber beetles from migrating into the harvested crop.
- Where cucumber beetles are a problem, let the beetles come out of hiding and plant late. They have a knack for finding vulnerable seedlings. When yours are up and growing, the cucumber beetles will be gone, fooled into thinking you don’t have any cucumbers in your garden.
- Natural predators include beneficial insects like braconid wasps, some nematodes, and soldier beetles.
- Companion planting your vegetables with flowers can help to keep pests away from the plants you don’t want the beetles to attack.
- Once the bacterial disease has entered the plant, there’s very little that you can do. If it’s bacterial wilt, you’ll see the leaves dry up, and the plant will quickly wilt and die. Take prevention for next year, as described above.
Catherine Boeckmann
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Your plants were attacked by the spotted cucumber beetle. You can use row covers before the veggies flower to keep them away from the plants. Or you can use organic pyrethrins or organic rotenone on the plants.
I am just finding out about these awful beetles and my garden has been established for over a month with my squash and now noticeably my cucumbers being destroyed. Are the few squash I have safe to eat? Or is it safe to say that my garden is contaminated and I need to rid of the plants? :(
Hi Sara,
Your squash is safe to eat. Try some of the remedies mentioned on this page to get rid of the beetles.
I tried the laundry detergent for cucumber beetles and it seems to be working. Also added beneficial nematodes the the soil hoping to kill off the larva. So far the beetles seem to be gone. In central Texas and our growing season has already started. On the look out for other pests now.
I have potted zucchini on my deck. Cucumber beatles are chewing through the leaves and spreading the zucchini wilt. I tried the dish soap trick and it worked. I put a bowl like a cerial bowl down next to the pots with a couple of drops of dish soap and water. Added a few drops of yellow food coloring for color. Its been down for 2 hrs and I have 5 cucumber beatles floating dead.
Cukes were doing great, suddenly I noticed a tiny hole in one so I cut it open & there was a small grub looking worm inside, checked others and they also had them. Pulled all plants,SAD, my question is the potting mix also compromised, or can I start again with same potting mix?
These might be pickleworms (Diaphania nitidalis). They are larvae of a moth, and bore holes into cucumbers and other cucurbits. They are a tropical/subtropical insect, and overwinter in southern Florida and southern Texas. However, each season, they can appear as far north as Canada. Depending on the climate, there can be several generations per year. Certain cucumber varieties, such as 'Gemini', are more resistant to pickleworms. Early planting also helps control this pest. Check for tiny worms feeding in flowers and buds; older worms will start to bore into the fruit; stems are sometimes tunneled into as well, causing wilting. Pupae overwinter in weeds or rolled leaves; remove rolled leaves and check for eggs on vines. Some recommend covering your crop with row covers overnight, to block the nocturnal moths from laying eggs on them; remove the covers during the day to allow bee pollination.
For more information, see:
https://utextension.tennessee.edu/publications/Documents/W206.pdf
Based on what I can find, it should be OK to re-use your potting mix, as long as all infested vegetation has been removed. If you live north of Florida, the pests will be killed from cold during the winter season.
I had great success with my first crop of yellow summer squash last year, I planted marigolds around the edges of my garden. I will do both this year; add the liquid detergent 'Gain' and plant the flowers, this will be my first attempt at cucumbers.
what mixture of gain detergent did you use to kill pest in garden or flowers?
Bug problems on my gourds...I am seeing the cucumber beetle and squash beetle on my gourds. Found several ideas here to try. But, I'm not getting flowers on the Luffa, and on the Bottle neck and Apple gourds, the flowers are drying up and dying or as the little female flower starts showing the hourglass shape, it's drying and dying off. What's going wrong?
