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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!

Photo Credit
Aaron Miyamoto

Learn to Identify and Prevent Cucumber Beetles

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 beetles and spotted cucumber beetle are specialists on cucurbits (cucumbers, squash, 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 female 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.

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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 one-third 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 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.

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: Whitney Cranshaw, Colorado State University.

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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. 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.

Garden Pests
About The Author
Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the website companion of The Old Farmer's Almanac. She covers gardening, plants, pest control, soil composition, seasonal and moon c...
Read More from Catherine Boeckmann

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Comments

<span>Karen Vaughn Davis</span> Thu, 03/26/2015 - 20:08
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.
<span>Sam</span> Fri, 05/27/2016 - 13:11
what mixture of gain detergent did you use to kill pest in garden or flowers?
<span>Marie Martinez</span> Sun, 08/03/2014 - 16:00
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?
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 08/04/2014 - 12:17

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.

 <span>Paul Karki</span> Sat, 07/26/2014 - 22:18
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?
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 07/28/2014 - 10:39

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.

 <span>Ruthanne Campbell</span> Mon, 07/14/2014 - 20:59
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!
<span>Nino</span> Tue, 06/10/2014 - 21:10
Finally I found a solution for cucumbers bugs....dead,,,,, I got this product in USA it called :ECO SMART ORGANIC ISECTICIDE, it is safe.
<span>Tyne@Kragnesfa…</span> Fri, 06/06/2014 - 09:35
I was wondering a little more about the flea beetle trick??
<span>Brock Ingham</span> Wed, 06/19/2013 - 14:40
thanks for the tips, i recently say a video of someone using a clove of garlic mixed with about 3 cups of water to liquefy then adding an additional 3 cups and letting it sit for a couple of days to ferment. once fermented mix with water (1 part garlic solution to 10 parts water). just about to make my batch now fingers crossed that it works.