Flea beetles hop from plant to plant, chewing tiny holes in leaves as they go.
We are not talking about the blood-sucking, disease-carrying fleas on squirrels. Instead, flea beetles are plant pests. Generally, they do not cause a lot of damage. After all, each flea beetle is only 1/16 to 1/8 of an inch long! If your plants are hosting enough of them, however, the damage can slow growth or provide points of entry for bigger problems. Let’s see what your plants are up against.
Flea beetle varieties
There are dozens of leaf beetle species. Here in the Bay Area, you are more likely to see these particular pests:
Flea beetle host plants
Flea beetles feed on many families of edible garden plants:
Also, carrots, corn, and sweet potatoes may find themselves on the menu. Flea beetles are also attracted to yarrow, but this is a good thing. Yarrow acts as an insectary. Beneficial insects have evolved to lay their eggs in plants such as yarrow, knowing that flea beetles and other pests will provide their young with an easy first meal. Other beneficials, such as big-eyed bugs, will also feed on flea beetles, so go easy on the pesticides. Pesticides don’t work very well on flea beetles anyway - they simply hop away.
Flea beetle damage
Pitting and small, irregular holes in leaves may merge to create raggedy areas. The holes are smaller than the damage caused by shot hole disease. Shot hole disease holes usually begin as 1/10 to 1/4 inch diameter red or purplish spots. There may be a pale green or yellow ring around each spot. As the dead tissue dries up and falls away, the shotgun blast look will appear. Small, irregular leaf holes may be caused by springtails, but it is more likely to be flea beetles. Fruits and roots may also be damaged by flea beetles.
Flea beetle lifecycle
Flea beetles lay tiny eggs in weeds, plant debris, and in the soil surrounding their favorite food plants. After the eggs hatch into thin, white larva, feeding may begin above or below ground. After a month or so, the larva pupate in the soil. When they emerge as adults, they use their big jumping legs to go wherever they want to feed.
Flea beetle control
Since pesticides are not very effective on flea beetles, other controls must be used, if control is actually needed. In most cases, it isn’t. If an infestation starts to cause serious damage, use basic sanitation in the garden. Removing all those tiny hiding places can make life difficult for flea beetles. Reflective mulch and white sticky traps can also be used, and row covers may block pests from reaching plants in the first place. Once they are present, you can lightly sprinkle the area with diatomaceous earth (DE). Apparently, flea beetles don’t care too much for sulfur, either.
Some commercial growers actually vacuum off heavy flea beetle infestations, but I don’t recommend it for the home gardener. You vacuum cleaner would never be the same!
You can grow a surprising amount of food in your own yard. Ask me how!