By Grant McCarty
Local Foods and Small Farms Educator, University of Illinois Extension
Now that you have planted your tomatoes and trellised them, it’s quite common to expect insect pests. Tomatoes tend to have a number of insect pests that can cause serious damage to leaf and fruit. Aphids, whiteflies, tomato fruit worm, and tobacco/tomato hornworm are the most frequent pests we see on tomatoes.
Aphids and whiteflies are tiny insects that can be hard to see and are usually on the tomato leaves. They tend to be more a nuisance but since they suck from the vascular tissue of the plant, overtime they may cause serious damage. You’ll know you have whiteflies after you have brushed up against plants and white flies will fly off. Aphids will be bright yellow/green in color. Generally, it can be hard to control both whiteflies and aphids although there are some chemical solutions available. Insect predators like spiders and certain wasps can also control aphids/whiteflies. For most growers of tomatoes, whiteflies and aphids are merely tolerated.
The two main culprits of extensive tomato damage are tomato fruit worm and tobacco/tomato hornworm. Both of these are light green in the larvae forms that are very noticeable in the garden.
Tomato fruitworm will enter into the actual fruit itself causing the fruit to not ripen and be inedible. You’ll know you have tomato fruitworm when you see a ripened tomato earlier than expected and as you pick it, will see a hole in it. Tomato/tobacco hornworm will be on the stems and leaves of the plant.
The actual size of hornworm can be between 2-3 inches long and because of the size, you can pick them off by hand and kill them. Sometimes the tomato fruitworm can be removed by hand if it has not entered the fruit yet. By removing either of these large insects, you will keep destructive pests away from your plants.
There are numerous tomato pest scouting guides available online that show what these look like. By looking at these guides, you’ll be prepared for the insects when they show up.