The following pests are considered the most common. Pictures of each of them are available on the web and can be obtained by doing a web search using the name of the pest. Additional tomato pests not covered here include cutworms, flea beetles, grasshoppers, spider mites, Colorado Potato Beetles, thrips, and root weevils.
1. Aphids – tiny, green to black soft-bodied, winged or wingless insects that cluster on the underside of leaves or on stems. They are sucking insects that can cause curled and distorted leaves & stunted plants. Localized aphid infestations can be hand-picked or pruned out or blasted off the plants with water. Applications of insecticidal soap, horticultural oil, or Neem oil may also be effective. Aphids are a favorite food of lady beetles. Damsel bugs and the larvae of lacewings and flower flies are also effective predators of aphids. Many tiny wasps act as parasites of aphids as well so use even organic pesticides with care.
2. Blister Beetles – slender gray, black, or striped beetles, 1/2 to 3/4 inch long. They eat the leaves of the plants but the larvae ( the gray ones) feed on grasshopper eggs and are therefore somewhat beneficial. They usually arrive late in the season (July-August) as mature adults that overwintered in the soil (fall tilling kills many). They begin to eat and breed, lay 50-300 eggs in the soil which hatch 10-21 days later. The larvae eat and molt thru 7 stages before returning to the soil for the winter. They can be hand-picked but wear gloves as they extrude a caustic fluid in self-defense. Chemical controls include pyrethrins and 5% Sevin.
3. Tomato Hornworm – are 3-4″ long green caterpillars with diagonal lines on sides, prominent horn on rear end. Eat foliage and may take bites out of green fruit. Tomato hornworms are the larvae of 2 large moths: the Hawkmoth and the Sphinx moth and overwinter in the soil in the pupal stage. Adult moths appear in late spring and lay single,
pearl colored eggs on the undersides of plant leaves that hatch in about a week. Larvae feed on foliage for about a month before they enter the soil and pupate. They can be difficult to spot as coloring matches plant. Look for them on the undersides of leaf-stripped branches. They can easily be hand-picked and destroyed or if infestation is severe, use Bt (Bacillius thuringiensis) dust. Braconid wasps will kill these caterpillars by implanting rice-like eggs on their backs and Trichogramma wasps parasitize the eggs.
4. Stink bugs – there are several species. Adults: Brown, green, or black; with or without markings; shield shaped; up to 5/8 inch long and 1/3 inch wide. Nymphs: Resemble adults but are smaller. Stink bugs discharge a foul odor.
Adults and nymphs suck sap from the plants and from the fruit. Plants are weakened; buds and young fruits are malformed. Yellow-white spots appear under the skin of the ripe fruit (Cloudy Spot). Control of weeds in the area of the garden helps to prevent some species of stinkbugs. Organic/Biological Control is to dust with sabadilla.
Chemical Control: Sevin 5% dust (Do not apply within 5 days of harvest.)
5. Tomato Fruitworms – are also referred to as the Corn Earworm. They are green, brown, or pink with light stripes along sides and on back; up to 1 and 3/4 inches long and are the larvae of various moths. The moths lay eggs near the stem of the green fruit and within 1 week the hatched larvae bores into the fruit where it feeds. It may move from fruit to fruit until it is ready to fall to the ground where it pupates till the following spring. Discard portions of fruit that have earworms in them. Disk or rototill plants immediately after harvest. Organic/Biological Control:
Parasitic Trichogramma sp. wasps parasitize tomato fruitworm eggs. Bt, (Bacillus thuringiensis) can be used for control of tomato fruitworm. Birds may feed on larvae. Moles and tilling destroy the pupae. Chemical Control:
Sevin 5% dust. Treat every 5-7 days when fruit begins to set as once inside the fruit the pesticide has little or no effect. Continue as long as fruit is present, if needed.