Cucumber Beetles

How to Identify and Get Rid of Cucumber Beetles

Cucumber Beetle
John Flannery/Wikimedia Commons

Share: 

Rate this Article: 

Average: 3.9 (323 votes)

Here are tips on how to identify, control, and get rid of cucumber beetles in the garden.

What are Cucumber Beetles?

If you find that the stems of your seedlings are being eaten off, leaves are yellowing and wilting, and holes are appearing, you may have a striped or spotted cucumber beetle problem. Striped cucumber beetles are specialists on cucurbits (such as cucumbers, squash, pumpkin, watermelons) while spotted cucumber beetles feed on other plants in addition to cucurbits.

Often, the beetles leave their hibernating sites early in the season (mid-April to early June), and feed on seedlings right as they are emerging, usually killing them. Then their larvae feed on the roots of the host plants. As they grow into adults (mid-July to September), the beetles will once again feed on the leaves, vines, and fruit of plants that survive, leaving deep marks in the rind.

Cucumber beetles hold another threat too: They can carry bacterial diseases and viruses from plant to plant, such as bacterial wilt and mosaic virus.

Identification

How to Identify Cucumber Beetles

Adult striped cucumber beetles are about ¼ inch 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.

Striped cucumber beetles. Photo by Whitney Cranshaw, Colorado State University.
Striped cucumber beetle feeding on cucurbit leaves, which will lead to stunted plant growth and the spread of bacterial wilt . Credit: Colorado State University.

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 population density 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.

Control and Prevention

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.
  • 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 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.

Spotted cucumber beetle. Photo by Shenandoah National Park.
Spotted cucumber beetle. Credit: Shenandoah National Park.

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 can be helpful to keep pests away. Plant tansy to repel cucumber beetles.
  • Once 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.

Plants Affected

Founder's Warehouse Sale

Topics

2020 Almanac Calendar Club

What do you want to read next?

Reader Comments

Leave a Comment

Quick question..!

Submitted by Tee on

Are the spotted ones sort of fuzzy too? I just found one crawling across the kitchen glass door and immediately trapped it under transparent tape so that I could take a closer look at what it was and whether or not it might be a harmful bug to my pug.

Oh nvm...

Submitted by Tee on

Oops nvm i was just looking at it too hard hehe thought i saw fuzz lol

Raid Mosquito and Fly spray works best

Submitted by Monica on

Cucumber beetles have been destroying our Chinese lanterns. After using both diatomaceous earth and spraying with Raid Mosquito and Fly spray, they have disappeared. Wouldn't use it on vegetable plants, though.

Cucumber beetles

Submitted by Rebecca Taylor on

I seem to have these on my flowers, cosmos & zinnias. Is this possible? I do not have a vegetable garden. They are eating blooms & leaves.

Cucumber Beetles on Flowers

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. 

cucumber beetles on flowers

Submitted by Dawn Rogers on

Rebecca I have a ton of them all over my mexican sunflowers. They have eaten tiny holes in the petals and also the petals of my cosmos.

Cucumber beetles

Submitted by Gail on

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!!!

Gourd looking cucumbers

Submitted by Molly on

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.

Misshapen Cucumbers

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 Cucumbers page.

tiny green with black striped insect

Submitted by Donna on

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

Submitted by Alysia on

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!

cucumber beetles

Submitted by Doris on

How much of what did you spray on your cucumbers; of water, cayenne pepper, garlic, and dish soap?

Black beetles with yellow and white spots

Submitted by Patronella Sello on

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?

Mustard Spinach

The Editors's picture

Submitted by The Editors on

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

Submitted by MartyM on

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?

Your plants were attacked by

  • 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

Submitted by Sara Gorrow on

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

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

Submitted by Jackie McE on

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.

dish soap works on cucumber beatles

Submitted by mike on

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,

Submitted by Errold Glw on

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

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....
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

Submitted by Karen Vaughn Davis on

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.

Gain detergent to kill pest in garden

Submitted by Sam on

what mixture of gain detergent did you use to kill pest in garden or flowers?

Bug problems on my gourds...I

Submitted by Marie Martinez on

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?

When the tiny female fruit

When the tiny female fruit shrivels and dies instead of developing, it's almost always a pollination issue. Do you have bees in the garden? Bees stay away if there are insecticides, rainy days, or extreme weather. You could always hand pollinate the female blooms. Just take the male stamen and brush it against the female in the morning when both blooms are open.

I see no evidence of cucumber

Submitted by Paul Karki on

I see no evidence of cucumber beetles or larvae, but the plants grow beautifully for 25-30 days and then the entire plant withers and dies. The root is rotted completely except for some fibrous material which, apparently the pests or fungus cannot digest. Any other possibilities, or any suggestions?

That's unfortunate, Paul. It

That's unfortunate, Paul. It sounds like a wilt, especially if there is no sign of beetles and the plants appear to thrive, until they fail fast. Fulsarium wilt survives in the soil for years. There are no chemical treatment for this; planting resistant varieties is the best advice.
There is also a bacterial wilt that can cause the plant to die off but it is carried in (yes, in) the beetles. They distribute it in excrement and the slow demise begins.

I put a yellow frisbee and a

Submitted by Ruthanne Campbell on

I put a yellow frisbee and a yellow bowl in my garden with water and dish soap in them and every day I see floating cucumber beetles and other bugs!

Finally I found a solution

Submitted by Nino on

Finally I found a solution for cucumbers bugs....dead,,,,, I got this product in USA it called :ECO SMART ORGANIC ISECTICIDE, it is safe.

Pages

FREE BEGINNER'S GARDEN GUIDE!

BONUS: You’ll also receive our Almanac Companion newsletter!

The Almanac Webcam

Almanac Headquarters Cam

Visit the Almanac HQ Webcam

Chosen for You from The Old Farmer's Store