Controlling Tomato Insects

Tomato hornworm caterpillars look huge when you encounter them in the tomato patch. They can devour tomato leaves and fruits quickly.

By Charlie Nordozzie
 

The tomatoes are finally growing strong with the warm July temperatures. But with new growth, flowers, and fruits, come some unwanted visitors to the tomato patch. In general, tomatoes don't attract a lot of insects, but there are a few you'll need to keep an eye out for, in case they get out of control.

The tomato or tobacco hornworm is a large caterpillar that can devour your tomato leaves and fruits overnight. They are a bit scary looking. They can grow up to 5 inches long and have a "horn" on one end. The horn won't sting you, but these caterpillars are imposing creatures. Gray moths lay eggs on the underside of tomato, potato, eggplant and pepper leaves in late spring. The eggs hatch and the hornworm caterpillars emerge to feed for about one month. Then they drop to the ground and pupate, and in warmer areas a second generation starts. If you're fearless, handpick the hornworms and feed them to chickens or just drop them into a pail of soapy water to kill them. You can also spray Bacillus thuringiensis, or Bt, on plants to control them. Bt is safe for the environment, but deadly for caterpillars.

Another pest you'll see is whiteflies. A few whiteflies aren't cause for concern, but since they reproduce so quickly they can get out of control before you know it. The small white eggs are laid on the underside of tomato, cucumber, lettuce, and many other plant leaves. Small, flat white larvae hatch from the eggs and within a month develop into adult whiteflies. Whiteflies exude a sticky substance called honeydew when they're feeding, so if you have sticky leaves, look for this pest. The larvae and adults suck juices from plant leaves, causing them to be stippled and yellow. Spray insecticidal soap on the underside of leaves to kill them. You may have to spray a number of times to kill newly hatching whiteflies.