Beetle Garden Pest Identification

Few situations are more disheartening than seeing garden pests damaging or destroying your garden plants. You can nip this problem in the bud, though, by recognizing pests such as certain beetles that feed on plants and by taking quick action to control them. It's also important to recognize beneficial beetles that help rid the garden of the destructive types.

Some destructive beetles are obvious invaders in the garden because of their size and other distinguishing characteristics.

Japanese beetles are relatively large, about 1/2 inch long, and they also stand out because of their brownish black, iridescent coloring. They're especially prevalent in the eastern United States, although they can appear in western regions. Japanese beetles infest and feed on many kinds of plants, including ornamental varieties and vegetables such as green beans (Phaseolus vulgaris). Their larvae are white and 1 inch long, and live in soil, where they chew and damage plant roots.

The Mexican bean beetle is another troublesome pest. It is about 1/4 inch long with a bronzy yellow back that has 16 black spots scattered on it. This pest is most common in the southeastern United States but can crop up elsewhere. Its larvae are plump, bright yellow, spiny and about 1/3 inch long. Both adult Mexican bean beetles and their larvae feed on leaves of all types of bean plants (Phaseolus spp.), leaving behind only the veins and making the leaves look like lace.

The Colorado potato beetle is quite distinctive, about 1/3 inch long with dark -brown stripes running down its yellow back. Most common in the eastern United States where winters are cold, it overwinters in soil then lays yellow eggs in spring on leaf undersides. Both the beetle and its red larvae, which have rows of black spots, feed on potatoes (Solanum tuberosum) and also attack other crops, including eggplant (Solanum melongena), peppers (Capsicum spp.) and tomato (Solanum lycopersicum).

Some beetle pests are quite small, making them hard to spot, especially when they're active and moving quickly. Often, the damage caused by these insects signals their presence.

Also known as the plum curculio beetle, the curculio beetle is tiny, no more than 1/4 inch long, with a dark body and a tiny, curved and elongated nose. It's mostly found in the northern part of the eastern United States and feeds on developing apple and pear fruits, making circular cuts in the fruit skin. The curculio beetle lays eggs in these cuts and, when larvae hatch from the eggs, the larvae burrow into the fruits and cause them to become deformed.

If you see a tiny, dark beetle that jumps like a flea when disturbed, then chances are good that it's a flea beetle. About 1/16 inch long, flea beetles emerge in spring after spending winter in garden debris, and they begin feeding on leaves, causing tiny holes in the foliage of vegetables such as cauliflower (Brassica oleracea var. botrytis), broccoli (Brassica oleracea var. italica) and eggplant. Flea beetles are especially active in hot, dry weather. Their larvae live in soil, where they feed on plant roots. Flea beetles also spread diseases called wilts to potato and corn (Zea mays) plants.

About 1/4 inch long, the asparagus beetle gets its name from its favorite food, the asparagus plant (Asparagus officinalis). An asparagus beetle can be either bluish black or orange with black spots, depending on its species. The beetle has a slim body and antennae, and feeds on young asparagus spears and, later, on the delicate foliage. Female asparagus beetles lay shiny, black eggs on asparagus leaves and spears. The larvae that hatch from the eggs start their generation's life cycle, and two to five generations appear each growing season.

Don't confuse beneficial ladybugs with beetle pests. Ladybugs have rounded bodies and are dark red or orange with black spots; their larvae resemble tiny alligators. Ladybugs eat many garden pests, including tiny, green aphids that suck plant juices.

The best control method for a beetle pest depends to some degree on the beetle's type. Hand-picking beetles from plants can be effective for some types -- asparagus beetles, Japanese beetles and Mexican bean beetles -- while others, such as cucumber beetles, can be controlled by placing floating row covers over plants early in the growing season to keep pests away. Clearing debris away from a planted area regularly can also help remove beetle hiding places and keep down the number of beetle eggs that hatch.