Pest Alert: Flea Beetles are Out!

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Have you seen this in your garden lately?

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Or this on your tomato plants??

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What about this on your cabbage or broccoli???

You've got flea beetles! One of our earliest garden pests has arrived. Learn more below.

What are they?

Flea beetles are a very common pest in vegetable gardens. Adult flea beetles are very small ranging in size from 1/16 –1/8th inch long. They are shiny black beetles that are quick and jumpy when you get close.


Flea beetles are pretty easy to see, and the damage they cause is even more obvious.  Adult flea beetles cause the most damage by feeding on foliage, cotyledons, and stems. As flea beetles feed, they create shallow pits and small rounded, irregular, holes (usually less than 1/8th inch) in the leaves, resulting in tiny shotgun hole appearance. They mostly affect radishes, broccoli, cabbage, turnips, eggplant, peppers, tomatoes, potatoes, spinach, and melons.   

Know your enemy:

Flea Beetles overwinter in the garden, taking advantage of plant litter, woody materials, and perennial vegetation.  In early spring, the adults become active and begin laying eggs in the soil. Following egg hatch, small white larvae feed on the roots of the newly planted seedlings, usually causing little to no damage to the plants (with the exception of potato flea beetle larvae). Adult flea beetles cause the most damage by feeding on the foliage.

A heavy flea beetle attack can result in wilted or stunted plants. Transplants can generally withstand more damage than plants started from seed, although both can be severely injured if flea beetle numbers are high. The good news is that adult flea beetle populations often decline throughout the summer, and most healthy plants can push through a flea beetle infestation. Once crops reach the 4- or 5-leaf stage, the plants are usually well established and can tolerate feeding damage. Give your plants an extra boost to beat the flea beetle by applying liquid fish emulsion fertilizer several times a week (follow all labeled directions). 

Treatment options:

  • Hand squish any beetles that you see and can get your hands on. They are a bit slower in the cool mornings and evenings.

  • Since these bugs jump and move around a lot, many can be caught in a sticky trap laid at the base of your infested plants.

  • Pyrethrin spray is a common treatment. It should be used sparingly as needed to kill flea beetles. Although this insecticide is acceptable by USDA organic standards, it should be used carefully since it can kill beneficial bugs too. Spray tops and bottoms of leaves on affected plants. Make sure it is organic or OMRI certified. No rotenone or synthetic pyrethroids.

  • Mix biodegradable dish soap with water into a spray bottle: 1 tablespoon of soap in a 1-liter spray bottle. Neem oil can also be added to this mixture. This should be applied on the tops and bottoms of the leaves of affected plants.

  • Fertilize and "baby" your plants. Healthy plants will overcome this seasonal pest. Choose healthy transplants, keep your plants well-watered, fertilize with an organic or sustainable fertilizer (see recommendation above), keep the area weed-free, and provide protection from frosts if needed. Stressed plants attract pests. Work to reduce any other stresses or competition to the plant.

Pest Workshop on Tuesday, June 18 @ 6 pm

Want to know more? Garden City Harvest and UM Dining Garden Manager Stasia Orkwiszewski are hosting a pest Workshop at the ASUM Community Gardens. All gardeners are welcome! Sign up by clicking the button below.

Organic Weed Management Workshop on Thursday, June 20 @ 6 pm

Join us at the Northside Community Gardens with the Missoula County Extension Weeds District staff for tips on organic weed management., including tips on how to deal with bindweed.

For our complete list of workshops this season, click the button below.