Flea Beetles, Flee!

Jesse Fulbright, MSU Liberty County Extension

I received my first flea beetle sample of the year just yesterday in the office.  Let’s spend some time learning about how to control them.

Flea beetles are small, black beetles that give an appearance of jumping when you try and capture them.  They will often leave a shotgun pattern of holes in various leafy vegetables, especially impacting vegetables when they are younger.  I’ve noticed them before on our plants but generally let nature run its course and the plants can sometimes outgrow their damage.  Here are some options that the University of Minnesota Extension have for control if you find that you have the pests as well.

First, some basic tips for flea beetle control; proper weed control in and around planting sites will deprive flea beetle larvae of food sources needed for successful development, and may help to lessen the flea beetle population. 

Floating row covers or other screening can exclude the beetles during seedling establishment and as crops advance.  However, remove row covers before the flowering stage to allow pollinating insects access to the plants.  I have also toyed with the idea of putting them back on afterwards for overall protection.

If you were thinking far enough ahead this year you might also have considered planting a trap crop, which can be successful in some situations.  Planting a highly favored crop such as radish before you plant your main crop can attract flea beetles away from the main crop.  Adult flea beetles will be attracted to the tallest, earliest crops available.  Once beetles are actively feeding in the trap crop, they can be sprayed with a labeled insecticide, or the crop can simply be harvested.

There are naturally occurring biological control agents that can aid in controlling flea beetles.  These will kill the adult flea beetle as the wasp emerges as well as sterilize the female flea beetle while developing in her body. 

There are many insecticides labeled for treating flea beetles.  The active ingredients in these insecticides include pyrethrins/pyrethrum, carbaryl, malathion, spinosad, permethrin and bifenthrin among others.   Look for those active ingredients when reading the label in the store.  Most flea beetle treatments are applied as foliar sprays to protect the foliage against the feeding of the adult beetle.  They will also have differing residual rates so pay attention to how often you might need to reapply an insecticide.