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How to Get Rid of Cucumber Beetles in the Garden

Striped cucumber beetle on a leaf

The Striped Cucumber Beetle has beautiful coloring, but it’s bad news for the gardener!

Image Credit:
Aaron Miyamoto
Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Finding small striped or spotted beetles on your cucurbit crops? They could be cucumber beetles! Here’s how to identify, control, and prevent 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.

Both the striped cucumber beetle and spotted cucumber beetle are specialists on cucurbits (cucumbers, squashes, and melons). The spotted beetle is also fond of corn and grasses.

  1. Often, the beetles leave their hibernating sites in early spring and immediately begin feeding on seedlings as they emerge, usually killing them.
  2. They disappear while the females lay eggs near the base on the plants, and then the larvae feed on the roots of the host plants.
  3. As they grow into adults (mid-July to September), the beetles will once again feed heavily on the leaves, vines, flowers, and fruit, leaving deep marks in the rind.
  4. Cucumber beetles pose another threat: As adults feed, they transmit bacterial wilt or mosaic virus, which causes plants to wilt and die.

Identification

How to Identify Cucumber Beetles

The adult striped cucumber beetle (shown in the photo above) is about a quarter of an inch long with a bright yellow abdomen, three black stripes down its wing covers, and a dark-colored head and antennae. 

Spotted cucumber beetles (shown below) are about a third of an inch long, bright greenish-yellow, with 12 black spots on their wing covers. 

spotted cucumber beetle on flower
The Spotted Cucumber Beetle. Pretty and destructive. Credit: John Flannery/Wikimedia Commons

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, yellowing, and wilting leaves. 

Feeding on flowers can reduce fruit production and direct feeding on fruit 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 they can be passed onto plants the next spring through fecal matter.

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

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 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. 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 that are 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 preventive steps for next year, as described above.

Garden Pests

About The Author

Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana.

Read more from Catherine Boeckmann

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Comments

<span>Monica</span> Wed, 07/04/2018 - 20:41
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.
<span>Rebecca Taylor</span> Fri, 10/06/2017 - 15:12
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.
<span>Dawn Rogers</span> Wed, 10/18/2017 - 20:01
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.
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 10/09/2017 - 14:34

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. 

 <span>Gail</span> Mon, 08/07/2017 - 12:13
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!!!
<span>Molly</span> Wed, 06/21/2017 - 18:33
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 title="View user profile." href="/author/editors">The Editors</a> Thu, 06/22/2017 - 12:19

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.

 <span>Donna</span> Wed, 06/21/2017 - 18:29
Destroying the leafs of all my flowers and herbs. Daisy, black eyed susans basil and more. How do I rid these
<span>Alysia</span> Mon, 05/29/2017 - 23:11
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!
<span>Doris</span> Thu, 06/28/2018 - 15:51
How much of what did you spray on your cucumbers; of water, cayenne pepper, garlic, and dish soap?