Dealing with Flea Beetles

Gardening with organic mulch has many benefits, but it also provides an ideal habitat for flea beetles. Here are some effective ways to deal with them.

I keep a 2,500 square foot vegetable garden that is perpetually mulched with whatever organic material I can find that will work as an effective mulch. The mulch is great for suppressing weeds, maintaining soil moisture levels, and it feeds soil organisms as it gradually breaks down - which are all great for plants. It's great stuff, but it has one drawback in that it creates an ideal habitat for flea beetles.

Photo by: James Lindsey at Ecology of Commanster

What are flea beetles?

Flea beetles are very small beetles. They come by their name honestly because they are the size of fleas, and they jump like fleas. They come in a range of colors (black/brown/blue/gray/striped) and can be spotted by the naked eye as little dark flecks on the foliage of plants. Flea beetle damage is easy to spot because affected plant leaves look like they have been blasted with bird-shot - such that they become full of tiny holes.

Many tiny holes are a tell-tale sign of a flea beetle problem.

Why are they a problem?

Flea beetles eat the leaves of plants. There are many types of flea beetles that feed on many types of plants - but the worst kind feed on the cotyledon leaves of newly emerging seedlings. Plants are particularly vulnerable at this stage of growth, and flea beetle damage can either set them back, stunt them, or kill them. It is also the case that plants weakened by flea beetle damage can be vulnerable to other pests - so a combination of flea beetles, slugs and snails can be devastating, and whole crops can be lost in a matter of days if the situation is left unchecked. As plants mature, some can shrug off a little flea beetle damage and simply “soldier on” while others become infested, and the foliage - while still edible - becomes very unappetizing. All that feeding also provides the energy for the successful breeding of larger future populations of flea beetles - which is not a good thing!

Plants are very vulnerable at the early stages of growth.