Cucumber Beetles

How to Identify and Get Rid of Cucumber Beetles

Cucumber Beetle
John Flannery/Wikimedia Commons

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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.

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Reader Comments

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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

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

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

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

I was wondering a little more

I was wondering a little more about the flea beetle trick??

thanks for the tips, i

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.

We grow organically and are

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.

I am going to try this tip. I

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 :)

I have never had the cucumber

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.

Debra, The stink bug is the

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.

hi what type of laundry soap

hi what type of laundry soap do you use is it dry or liquid soap please anwser needed asap thank you

I have found a few cucumber

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!

I was wondering what kind of

I was wondering what kind of detergent you use. How about dryer sheets? Would that work too?

Any strong smelling laundry

The Editors's picture

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

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