Learn to Identify and Prevent Cucumber Beetles
How to Identify Cucumber Beetles
Adult striped cucumber beetles are about ÂĽ 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 Almanac 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
Sprinkling finely crushed eggshells and or DE at swwd planting time will kill emerging larvae.
Please don't use sticky traps! I got them for the first-time last year and within a week I had a poor bird stuck on one, and it was still alive when I found it, so I had to humanely euthanize it. those traps can catch ANYTHING that comes along, including pollinators, birds, frogs, amphibians, even small mammals. I still feel bad about that bird. My yard is full of wildlife. those traps are terrible.
If you “catch” something in a sticky trap that you didn’t intend to catch, you simply use olive oil (or vegetable oil, mineral oil, and even baby oil in a pinch) to get it unstuck. Before you use the oil, it’s best you cover the remaining part of the trap that is sticky with newspaper, or paper towel, cornstarch, cornmeal…etc so it doesn’t get “stuck” again as your releasing it. Stay calm and speak calmly and softly, move slowly as you are putting the oil around the parts that are stuck…and don’t be heavy handed with the oil. Use only the amount needed to “dissolve” the glue.
Better to not use sticky traps at all. Not humane
Thank you! Very instructive.
I find catching these cucumber beetles easy. I usually always find them in the male flowers of my squash plants. Of the 10 I have caught in the last couple of days, 7 were in the squash flowers in the front of the house. Three were in the backyard on squash leaves, which did not have any flowers. To catch them I use eye tweezers on the flowers and just my fingers on the leaves.
Why do I have Cucumber Beetles on my roses? How do I get rid of them? They're living in my roses and eating the roses. Thanks!
Yes, the adults can cause minor damage to rose petals. Choose a pesticide that has a low impact on natural enemies, such as lady beetles and pollinators. Neem is a plant based pesticide that prevents insects from feeding, which eventually kills them. Pyrethrins have no residual and treatments need to come in contact with the beetles to be effective. Finally, there are broad-spectrum pesticides (permethrin, bifenthrin, lambda-cyhalothrin and carbaryl) but we don’t use them since they kill beneficial insects, too.
Kathy,
The hard orange worms inside the roots/stems of your plants sound like wireworms. There are possibly beneficial nematodes available.. ..or maybe have chickens there to scratch for a while.
They are small and appear to eat thru the skin.
