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Cucumber Beetles in the Home Vegetable Garden

The term cucumber beetle is a generic term for nearly ten types of cucurbit-hungry leaf beetles each with very similar, but slightly different markings from one another.

While there are more than 1,500 different leaf-eating beetles in North America alone, only a few of them are truly considered cucumber beetles known to feed almost exclusively on fruiting crops within the cucurbit family. Some types of cucumber beetles such as the banded or spotted cucumber beetles have larger appetites that extend into other parts of the garden such as brassicas and various ornamental flowers.

When compared to the more troublesome Japanese beetle and Colorado potato beetle, a cucumber beetle infestation can generally be treated with a yellow sticky trap, available scented like cucumber and melon specifically for cucumber beetles.

Facts About Cucumber Beetle Garden Pests

  • Cucumber Beetle Distribution: About 10 species of Acalymma and Diabrotica found widely east of the Rockies with few populations on the west coast
  • Cucumber Beetle Host Plants: Cucurbits such as cucumber, cantaloupe, watermelon, zucchini, pumpkin, summer and winter squash
  • Cucumber Beetle Lifespan: 8-9 weeks
  • Cucumber Beetle Eggs Laid per Lifetime: ~1,200-1,500
  • Cucumber Beetle Removal: Yellow scented sticky traps, neem oil, castile spray, BT spray (Bacillus Thuringiensis)
  • Cucumber Beetle Predators: Ladybugs, lacewings, spiders, grasshoppers, tachinid flies, birds
  • Most Common Cucumber Beetle in North America: Striped Cucumber Beetle (Acalymma vittatum)

What Do Cucumber Beetles Look Like?

The term cucumber beetle is a generic term for nearly ten types of cucurbit-hungry leaf beetles each with very similar, but slightly different markings from one another.

The two most common in North America, the striped (Acalymma vittatum) and Western striped (Acalymma trivittatum) cucumber beetles, share three distinct black lines that run the length of their bright yellow bodies.

Spotted cucumber beetles (Diabrotica undecimpunctata) have the same black and yellow color palette, except that their bodies are spotted almost identically to ladybug markings. Banded cucumber beetles (Diabrotica balteata) have a similar spotting except boast an exotic yellow and teal as opposed to yellow and black.

Both the Northern and Western corn rootworms (Diabrotica virgifera) are considered a cucumber beetle, sharing the same rounded arthropod shape but with a lime green, nearly translucent body.

Cucumber Beetle Damage to Garden Vegetables

Similar to the Colorado potato beetle, the cucumber beetle is especially troublesome in the garden because it will feed indiscriminately on a host plant in all four larval stages all the way into adulthood.

For most insects such as moths and butterflies, it is only the young developing larvae that cause vegetative damage, while the adult pupae mature into beneficial insects that feed on more bothersome garden pests. But cucumber beetles are not as useful and feed on roots beneath the soil as larval grubs, maturing into instars that chew directly on leaves and fruit like any leaf-eating beetle.

Rather than feeding on the roots, some larvae may chew through the rinds of developing fruit and quickly spoil a harvest.

What Do Cucumber Beetles Eat in the Garden?

While there are more than 1,500 different leaf-eating beetles in North America alone, only a few of them are considered cucumber beetles known to feed almost exclusively on fruiting crops within the Cucurbitaceae family.

Cucumber beetles will feed on cucurbits such as cucumbers, melons, and winter and summer squash at every stage of life from young seedling up until the harvest. Some types of cucumber beetles such as the banded or spotted cucumber beetles have larger appetites that extend into other parts of the garden such as brassicas and various ornamental flowers.

Both the Northern and Western corn rootworms are considered a type of cucumber beetle but, rather than feeding on cucurbits, will solely feed on corn crops from the roots up to the silks.

Cucumber Beetle Eggs

Some cucumber beetles such as the common striped cucumber beetle will lay eggs very similar in color, shape, size, and patterning to other beetles and common pests. Female adults generally lay about 12-36 eggs at a time beneath developed true leaves so the newly hatched larval grubs have protection and an immediate source of food, up to 1,500 per life.

Eggs spotted on one plant can be indicative of eggs on surrounding cucurbits because cucumber beetles are able to fly to nearby plants to lay several dozen more clusters of eggs.

Some cucumber beetles bury their eggs in the soil near the developing roots as both a source of protection and food. Eggs hatch in about 14-21 days and, if found, immediately killing the eggs is the absolute best way to minimize an infestation.

How To Rid Cucumber Beetles from the Home Garden

Yellow sticky traps are the most effective way to rid your garden of cucumber beetles because the yellow replicates the same color produced by flowering cucumber, melon, and squash plants. Some are sold specifically for cucumber beetles, scented like melon and cucumber for additional allure.

Organic neem oil, castile soap spray, and organic BT (Bacillus Thuringiensis) are known to be effective on cucumber beetles, but only while in their soft-bodied larval stage.

Cucumber beetles are hard-shelled arthropods that can be difficult to eradicate if not spotted early. Once matured, oils and sprays generally will not kill cucumber beetles but may only make the host plant less appetizing.

Simply checking for eggs on the underside of leaves is the most effective way to minimize the spread of cucumber beetles.

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