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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Striped cucumber beetles typically stick only to cucumbers, squash, and related vegetables, but spotted cucumber beetles are known to be much less picky. It could certainly be these beetles that you’re seeing on your flowers.
I have found that killing the beetles by hand at night works. I have sprayed them with water to prevent them from flying. Then kill them by hand. Also neem oil seems to help. My latest discover is to use a bright flashlight at night, usually around 10:30, against my garden box wall... don't spray with water because you want them to fly. The beetles flock to it like moths and are easy to squash by hand or spray with neem oil. I think I might try the alcohol spray on them against the box since I wouldn't be spraying the plants. An added note of interest.... one night a rattlesnake slithered three inches past my foot!! Yes!! They really are out at night!!!
This is our first garden. We have planted the Bonnie Cucumber Burpless plants. The plants have done well growing but now that it is time for the cucumbers to start growing they are growing in odd shapes. They look more like gourds. Weirdly shaped, like curly q's. Need advice on what we are doing wrong.
A number of online reviews of the Bonnie Burpless Hybrid claim to have had similar issues with misshapen fruits, so these weird cukes could be a result of the variety—not your care! Perhaps try the similar Burpless Bush Hybrid, which seems to have better results, or one of the varieties listed on our page.
Destroying the leafs of all my flowers and herbs. Daisy, black eyed susans basil and more. How do I rid these
I came home from a five day trip to find a bunch of these beetles on my 4 cucumber plants. They are still pretty young, but almost two feet now. Looked up what they were and took action right away because I do not want to lose my plants! I had a great harvest last year with the organic cucumber plants from Bonnie, without any bug/fungus problems.
So here is the timeline:
Thursday evening, came home and saw about 20 beetles. Sprayed all of my plants with a mixture of water, garlic, cayenne pepper, and dishsoap.
Friday, picked off about 6 beetles.
Saturday, picked off about 4, saw two fly away.
Sunday and today, no beetles.
I check in the early morning/evening.
Just gave them another small spritz, hopefully it's enough to keep them away for good. Can't seem to find any larvae, but I do have a heavy woodchip mulch. Also, I found most of the beetles inside of the flowers, only a couple on the leaves. Not much damage except at the base of a few older leaves.
I hope anyone can find this helpful if they are having this problem too!
How much of what did you spray on your cucumbers; of water, cayenne pepper, garlic, and dish soap?
I planted a whole lot of mixed veggies and find that I have some black beetles with yellow and white spots eating what I suspect to be my mustard spinach. Everything else (including normal spinach) is fine. Any ideas what this is and how I can control it without harmful pesticides?
The only real pest mustard spinach is susceptible to is a flea beetle (there are many types, including a spotted species), which is hard to control. Protecting plants with barriers such as a row cover before infestation is the best management strategy. Before putting the garden to bed for the winter, remove all old debris from your infested plants. Since flea beetles overwinter in the soil, try hoeing and cultivating in the early spring to destroy the larvae. Add a thick layer of mulch around young plants to prevent the beetles from jumping up on to the leaves. Place some sticky traps nearby to try to capture those that persist.
I have successfully grown cucumbers for the last two years and several different varieties of them. I live in St. Louis MO. I have tried in the past and several times to grow squash, and cantaloupe and watermelon all to no avail.
The pest that made me give up was not the cucumber beetle, it was a beetle that is green with black spots. Apparently they were infecting the plants with the wilt, and the plants would just die in a matter of days. I tried everything to keep them out and off the plants but they won. I no longer plant any of these plants as I was never able to get any produce. There were literally hundreds of them. My yard and garden does not have any trashy areas for them to over winter in.
Since this is not the black and yellow striped cucumber beetle what is it? It is certainly as devastating as the cucumber beetle.
What are these beetles and is there any way to control them?
