What are Flea Beetles?

Flea beetles is the general name applied to the beetles of the leaf beetle family (Chrysomelidae) that feed on the surface of leaves, stems and petals giving the appearance of small shotgun holes all over plants. Flea beetles get their name from their ability to jump like fleas when disturbed and are a common pest of vegetable crops. They can be found on flowers, ornamental shrubs and occasionally trees.

An elegant metallic blue adult flea beetle ready to leap away!

An elegant metallic blue adult flea beetle ready to leap away!

Different species attack different plants and they are notoriously hard to control because all locales have several species of flea beetles hiding in wait. They are known to eat tiny holes into leaves of arugula, beans, beets, broccoli, Brussels sprouts, cabbages, cauliflower, collards, corn, daikon, kale, lettuce, mustard, eggplant, pepper, radish, rocket, tomato, potato, sweet potato, spinach, Swede, squashes, turnips and related family plants. Seedlings and small plants are more vulnerable to damage from flea beetle attacks.

Identifying Flea Beetles:

Adult flea beetles emerge from the soil in early spring after overwintering under soil and leaf litter, preferring brushy and woody areas rather than grassy ones. Adults are quite small, sizes ranging from 1/16 to 1/8 inch long with enlarged hind legs that help them leap away. They come as black, brown, gray, bronze, bluish and other metallic colored shiny beetles with some being striped too, depending on the species.

Females lay their eggs at the base of plants near the soil and sometimes even on leaves. Eggs hatch in 1-2 weeks. Larvae are thin, white legless grubs with brownish heads. They feed on the roots of the plant till fully grown. They then pupate in the soil for about 2 weeks before emerging as adults.

Flea beetle eggs are generally found on the underside of leaves.

Flea beetle eggs are generally found on the underside of leaves.

Organic Control and Preventative Measures:

1. Plant or transplant susceptible crops into the garden as late as possible to avoid attacks from the early emerging flea beetles. Set out large healthy transplants rather than sowing seeds directly in the garden.

2. Trap crop method: This method involves growing plants that are more favorable to flea beetles than the crop you are trying to protect. Plant these trap crops all around the corners of your garden, several feet away from your precious vegetables. Giant mustard plants and radishes are good trap crops. Pull up and destroy or spray the plant with insecticide to ensure they don’t move further into the garden.

3. Remove and dispose of all weeds and crop debris from the growing area to ensure elimination of flea beetle habitats in your garden. Digging up the soil is also a good practice to kill over-wintering adults.

4. Since handpicking is not an option, household and handheld vacuums to suck away flea beetles can be effective in reducing pest numbers.

5. Mulching the ground around your plants can make it difficult for female beetles to lay eggs on the base of plants.

Flea beetle larvae.

Flea beetle larvae.

6. Attract or obtain beneficial insects such as baraconid wasps, soil-dwelling nematodes and the tachinid fly. Daisies, cosmos, yarrow, alyssum, dill, fennel, angelica, clover and cone-flower all help attract beneficial insects.

7. Plant vulnerable plants that are tolerable to shade in shaded areas. Flea beetles prefer the sun.

8. Plant resistant varieties that include ones with hairy or waxy leaves.

9. Inter-planting cabbages or broccoli with radishes can help save them as flea beetles prefer radishes.

10. Cover seedlings with fine insect proof netting to avoid damage from adult beetles.

Affected leaves look like they've been peppered by a tiny shotgun!

Affected leaves look like they’ve been peppered by a tiny shotgun!

11. Food grade diatomaceous earth spread on affected plants is excellent for reducing feeding on plants by adult flea beetles. It can also be used as a preventative measure.

12. Neem oil has been found to be useful against flea beetle populations.

13. Try a homemade spray such as the following: 2 parts rubbing alcohol, 5 parts water and 1 tablespoon organic liquid soap on susceptible plants. Garlic and pepper sprays and catnip tea sprays have been found to be effective too.

14. Sticky yellow traps will catch flea beetles but will deceive some beneficial insects too.

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