Having trouble with flea beetles in your garden? Here’s how to identify, prevent, and get rid of flea beetles so that they stop eating your crops!
What Are Flea Beetles?
Flea beetles are small, shiny-coated beetles with large rear legs, which allow them to jump like fleas when threatened.
There are many species of flea beetles. Some species attack a wide range of plants, while others target only certain plant families. In the garden, a number of vegetable crops are susceptible to these pests, particularly those in the Brassica family, like broccoli, cabbage, kale, radishes, and turnips, as well as Nightshades such as tomatoes, peppers, and eggplants.
How to Identify Flea Beetles
Given that there are so many species of flea beetles, they vary in appearance quite a bit. Colors range from black to tan, with other, brighter colors mixed in, and the beetles may have a solid, striped, or spotted pattern depending on the species.
To identify flea beetles, it’s easier to look for signs of their damage (described below) than for the beetles themselves. At only 1/16 of an inch in length, flea beetles are very tiny and will quickly spring away—like fleas—if they see you approach!
When Do Flea Beetles Appear?
Adult flea beetles overwinter in brush and wooded areas. Adults pose the biggest threat early in the planting season as they are emerging, typically when outdoor temperatures reach 50ºF (10°C). At this time, seedlings are being planted, too, and they are most susceptible to beetle damage.
Eggs are laid at the base of plant stems in early summer after the spring feeding period, and larvae feed at the roots.
Flea Beetle Damage
Adult beetles feed on foliage, producing “shotholes” in the leaves. Look out for these holes especially on young seedlings, where damage is most rapid and will cause the most harm. The holes they make will be round and can quickly ruin leafy greens. New leaves are usually damaged first, and they will have a lacy appearance.
Flea beetles usually don’t cause fatal damage to established plants because the leaves are already large enough to survive a few holes. The real danger is that the beetles can spread bacterial diseases, such as wilt and blight, from plant to plant. Additionally, in leafy crops like lettuce or spinach, the holes can bring down the quality of the leaves. Therefore, they are still important to consider a pest.
Photo Credit: University of California White Mountain Research Center. Flea beetles can cause leaves to appear lacy after they’ve caused a lot of damage.
Control and Prevention
How to Get Rid of Flea Beetles
Try this homemade spray to control flea beetles: 2 cups isopropyl alcohol, 5 cups water, and 1 tablespoon liquid soap. Test out the mixture on a leaf of the plant, let it sit overnight, then spray the rest of the plant if you don’t notice any adverse effects. Spray the mixture on the foliage of garden plants that are susceptible to these pests.
Use white sticky traps to capture flea beetles as they jump.
Insecticides may be used early in the season, but are generally unnecessary in the control of flea beetles on adult plants. Be extra diligent if your soil has history of bacterial diseases. Please contact your local nursery or cooperative extension for further advice.
Photo Credit: Jeff Hahn, University of Minnesota Extension. If you didn’t take preventative measures, it might be impossible to stop the flea beetle damage.
How to Prevent Flea Beetles
In the spring, emerging flea beetles will be waiting to feast on your garden. Cut off their food supply by delaying transplanting or planting by a couple weeks if possible.
In the fall, till the garden to unearth any hiding flea beetles. This will also make soil easier to work the next spring.
Row covers may be successful at keeping these pests out, as long as they are completely sealed. They should be used immediately after transplanting, so the pests do not have time to find the plant.
Flea beetles can be kept away from crops by planting strongly-scented plants such as catnip, sage, mint, or hyssop nearby. Nasturtium, radishes, and basil can be used as “trap crops” to take the beetles’ focus off of more valuable plants.