Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
Contrary to their name, cucumber beetles prey on more than cucumbers. Their preferred menu includes any plant in the cucurbit family: cucumbers, melons, squash and pumpkins. They not only destroy plants by eating them but they are also a vector for disease, spreading bacterial wilt and mosaic virus for which there are no remedies other than to remove the diseased plants from your garden and compost them.
Cucumber beetles come in four varieties: Eastern and Western Striped Cucumber Beetles and Eastern and Western Spotted Cucumber Beetles. To rid your garden of them, it is important to understand their lifecycle.
What are Cucumber Beetles?
Adult cucumber beetles overwinter in your yard amongst woody areas and the weeds and garden debris that are left over from the growing season. When spring arrives and the temperature reached the mid-50’s, they emerge and start eating the leaves and petals of any available flowering plants. As the season progresses and temperatures continue to rise, they switch to their preferred menu of cucurbits as those seeds germinate. The beetles favor the stems and leaves.
They also begin mating. The female striped cucumber beetle can lay up to 1500 eggs in her short two month lifetime. The female spotted cucumber beetle “only” lays 200 to 300 eggs. The eggs are laid in the soil close to your cucurbits. When they hatch, the larvae eat the roots of your plants.
The southern US with its warmer temperatures and longer growing season supports up to three generations of cucumber beetles each year. The colder northern US usually sees only two generations.
Now that you know a little bit about their lifecycle, here are some suggestions for ridding your garden of these pests.
Plant Your Cucurbits Two Weeks Later
Try planting your cucurbits two weeks later than you normally would. Cucumber beetles are not the smartest creatures and when no cucurbits appear, they will think that no cucurbits will be grown in your garden so they will move on to your neighbors' gardens in search of their favorite food.
Use a Trap Crop
You can also try planting a “trap crop”. Trap crops are plants that are eaten by a pest that you don't mind being damaged. If you are trying to grow cucumbers, plant another cucurbit around the perimeter of your cucumber patch. Blue Hubbard squash is usually recommended because it can withstand being eaten by cucumber beetles and is resistant to bacterial wilt which they can carry.
Barriers are an effective deterrent.
Floating Row Covers Plant your cucurbits under floating row covers. Just remember to remove them for a few hours a day while your plants are flowering to ensure pollination. If the cucumber beetles can’t reach them, neither can the pollinators.
Foil Place foil around your plants. Cucumber beetles don’t like the reflectiveness.
Mulch Use mulch around your plants to deter cucumber beetles from laying their eggs near your plants. You can use your normal straw or hay mulch or use the foliage from plants that repel cucumber beetles like radishes, tansy and nasturtium.
You can also plant radishes, tansy and nasturtium amongst your cucurbits to make them less inviting to cucumber beetles.
Use Beneficial Insects
Plant flowers like marigolds, sunflowers, daisies and alyssum, or herbs such as borage, catnip, calendula and dill to attract beneficial insects which view cucumber beetles as lunch. You want to attract predators such as soldier beetles, braconid wasps and tachnid flies. Nematodes which live in the soil will eat cucumber beetle larvae after they hatch but before they can damage the roots of your cucurbits.
Handpick Cucumber Beetles Off of Your Plants
If you are not too squeamish, you can handpick cucumber beetles off of your plants. Do it in the mornings and evenings when they are less active. During the day, they will fly away faster than you can grab them. Wear yellow, which they find attractive, so that when they do fly away, it will be only as far as your shirt. Kill the beetles by either squishing them or dumping them into a container of soapy water.
Use Chickens to Eat Cucumber Beetles
Chickens love insects and grubs! If you raise chickens, or have a neighbor who is willing to lend you their chickens for a few hours in the evening, you can set up a temporary pen around your cucurbits and allow the hens to help themselves to an evening snack of cucumber beetles on your plants as well as their larvae in the soil.
Fall Cleanup Is Imperative
The most important step you can take to prevent cucumber beetles from destroying your cucurbits is to prevent them from overwintering in your garden. Remove all debris, dead plants and weeds from your garden in the fall and do a deep tilling. The cleanup deprives them of hiding places for the winter and the deep tilling exposes any hidden beetles to the harsh winter weather which will kill them.
A severe infestation of cucumber beetles can destroy your cucurbits within weeks. There are simple, organic steps that you can take to reduce the number of cucumber beetles and minimize the damage they inflict and the diseases which they carry.
Questions & Answers
Question: Can I use pesticide for cucumber beetles? If there is one, what is the name?
Answer: It is never recommended to use pesticides on edible plants. If it is harmful to the insects that eat the plants, it is also harmful to the humans who eat the plants. What you want to do is exclude the adults from your garden so that they can't lay eggs which will hatch into larvae which will eat the roots of your plants. Cover your plants so that the adults can't get to them to lay their eggs. Use a trap crop to lure them away. Or even just wait two weeks longer to plant your cucurbits so that the beetles will leave your garden in search of something else to eat.
© 2014 Caren White
Caren White (author) on May 31, 2014:
I grow a lot of herbs so I am always happy to find yet another use for them. Thanks for the pin! I'm starting to get traffic from Pinterest.
FlourishAnyway from USA on May 28, 2014:
Good tips, especially the marigold and catnip. Voted up and pinning.