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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>Cornflower</span> Sun, 03/11/2012 - 21:27
We grow organically and are always looking for effective ways of minimizing insect damage and over the years we have learned a few "tricks". Yes we plant the beans late for our area (south shore Nova Scotia)usually around the first week of July and miss the bean beetle cycle. For the cucumber beetle and potato beetle I place glass jars with about an inch of heavily perfumed laundry soap every 10 feet along the rows partially dug in to avoid spillage. Just poke a few holes in the lids for the scent to escape and we no longer spends hours handpicking these beetles off. It really does work. Just add more as needed. We still see the insects around the edge of the garden but the perfume does not allow them to find the plants you are protecting. Fleas beetles...till the soil and seaweed. Aphids are dealt with by mixing sodium borate (borax) with icing sugar and place in small plastic tubs with holes near the base large enough for ants to get into. Place at the base of your apple trees and other plants affected by them. You will spend a lot less time picking off insects leaving more time to weed. :) Remember not to mow around your fruit trees leaving your dandelions to bloom and attract the bees till your trees are ready to blossom out, then mow. We also encourage toads by placing inverted clay flower pots here and there. Happy gardening everyone in 2012.
<span>Cghpnd</span> Wed, 08/13/2014 - 20:19
I was wondering what kind of detergent you use. How about dryer sheets? Would that work too?
<a title="View user profile." href="/author/editors">The Editors</a> Thu, 08/14/2014 - 10:39

Any strong smelling laundry soap will do. You can try dryer sheets.

 <span>Colman242003</span> Wed, 07/10/2013 - 11:01
I have found a few cucumber beetles inside blooms. Will this trick drive them away? I was wondering the same thing someone else asked...liquid or dry detergent? want to try right away before I get an infestation!
<span>Wayne Desnoyers</span> Tue, 07/17/2012 - 16:57
hi what type of laundry soap do you use is it dry or liquid soap please anwser needed asap thank you
<span>Debra Pretko</span> Sat, 06/02/2012 - 07:10
I am going to try this tip. I have had trouble growing summer squash as well as cucumbers. I have tried everything on the market and everything I have read this far with no luck. I have been trying for 23 years. So here goes number 24. Thanks :)
<span>Doug 2</span> Sun, 07/20/2014 - 23:19
Debra, The stink bug is the worst enemy of squash. First solution that has worked 100% FOR ME. OUT OF 9 PLANTS THIS YEAR HAVE PICKED AT LEAST 150 LBS. OF ZUCCHINI SQUASH. Two people, one on each side of plant. Take hose and flood stem of plant. They spend their time under the stem root. When they come up for air, squash them. I have killed at least 40 of them this way and none have had time to lay their little red eggs under the leaves.
<span>Karen Cass</span> Sat, 06/29/2013 - 16:18
I have never had the cucumber beetle before.I bought from a different com.now its invested.Im so upset I will try ypur advise.Im in Nova Scotia.