These little cuties are unfortunately a huge issue for many tomato growers. The adult beetles are generally small—a fourth of an inch or smaller—and can spring in the air when disturbed (hence the “flea” part of their common name). If you look closely at their hind legs, you’ll see enlarged legs, much like a grasshopper. Many are shiny or even brightly colored. The larvae are small, slender, and pale.
The adults mostly attack seedling plants and fresh leaves. They chew fairly distinct holes in the plants, which can severely damage them. Mature plants that are damaged rarely result in significant loss. [ae1] The larvae are also known to feed on the roots but aren’t known to cause significant damage. These can also feed on the tomato fruits, especially late in the season. The damage resembles that of pinworms or early instar fruitworms.
These are most active early in the growing season. They cause the most damage during hot and dry weather.
They have a worldwide distribution in temperate and tropical locations.
Having a monoculture (one type of crop) causes a disruption in the local ecosystem. This allows pests to get out of control because their competition and natural predators are no longer around.
Rotating your crops is one way to keep flea beetles in check. There is evidence that they overwinter in the soil, so rotating with a plant that is not a host will help. Also, intercropping with plants such as catnip and mint may discourage feeding by disguising your tomatoes. If you have a large infestation, spraying pyrethrin (as a last resort) has shown to be very effective and organically accepted.
Though many species of this beetle are considered pests, some are used as beneficials for weed control. One example is the control of the invasive weed known as leafy spurge (Euphorbia esula)—because of its toxic latex, most herbivores avoid it, except one genus of flea beetle, Aphthona.