We Have Holes in Our Tomatoes!

Q. I have Early Girl green tomatoes with round holes in three of them. Otherwise plant is in great shape. Other fruits on plant OK. .

A. That is feeding damage probably by the tomato fruitworm. Applications of Bt or spinosad should slow them down and are “organic” controls.This is basically the same “worm” that attacks the ears of corn by laying its eggs on the new silk coming from the forming ears.

The tomato fruitworm is probably the most damaging pest to tomato fruits. As the name implies, the damaging part of this insects lifecycle is the “worm” stage or more properly called “larva”.

Click here to see the larva or immature form before it becomes a moth

They don’t all come in one color so they can range in colors from pale yellow, to red, green or even brown with pale stripes down its length. They are about an inch and a half long when fully grown but they can be smaller than this if they are not yet mature.

Unlike hornworms which are pretty easy to spot during the day or at night  with a black light because they glow green,  fruitworms you wont see until you see damage to the tomato fruit. With your black light you can go scouting for hornworms and scorpions at the same time!

The adult of the fruitworm is a night-flying moths that ranges in color from tan to brown with orange in it. They are about 1 to 1 1/4 inch across their wingspan.

Click here to see the adult moth

Because they fly at night that’s when the egg laying occurs.They like to lay their eggs on tomato leaves close to green fruit or they might lay them on the leaves on the outer edge of the plant if the plant is dense. They are flying now and have been flying for quite some time.

Click here to see a close-up of an egg

The eggs that they lay are very difficult to see because they are so small.The eggs are white when first laid and then develop a brown stripe or mark just before they’re ready to hatch. First they begin to feed on leaves before they attack the fruit. They prefer to feed on green fruit and the damage that they create by tunneling into the fruit causes the tomatoes to ripen more quickly. The fruit is pretty well demolished once they enter and feed and move on to a new fruit.

Shining a white light or black light against a white sheet at night is an easy way to see if they are flying.  You can try it now and you will probably attract some but the best time is when tomatoes begin to flower so you can time your spraying.

You can also use pheremone traps.

Black light or even light traps serve as a good indicator when these guys are flying and will be a problem in the garden in the future. This is a cool way to look for them and great to show kids and grandkids.