Fruitworms (Species: Helicoverpa zea). This moth species belongs to the dreaded family of moths called Noctuidae. Within this family, you can find other agricultural pests often referred to as cutworms. This species goes by several common names because they are polyphagous (they feed on a variety of plants); the most popular include corn earworm, cotton bollworm, and tomato fruitworm. They come in a variety of colors, including cream, brown, and green, and are around 1.5–2 inches long (3.8–5 centimeters) during their last instar.
Tomato fruitworms typically attack buds, flowers, and fruits of tomato plants, giving them their common name. Deep holes in tomatoes are generally indicative of fruitworm activity.
The adults start laying eggs in spring. Larvae will feed on foliage until fruits begin to develop. There can be two to three generations a year lasting through the fall, unless they’re in tropical or greenhouse conditions.
This species is primarily in North and South America, but invasions on other continents have been reported.
Having corn, cotton, soybean, or other favorite plants nearby can attract the adult moths to your tomato garden. Even without other neighboring crops, the moths can and will find your plants if you’re in an active area.
Prevention such as monitoring adult activity with pheromone or light traps is the easiest form of control. Insecticidal soaps and oils, as well as a Bt (Bacillus thuringiensis) product, can be effective, but many people resort to pesticides. Know that once larvae enter the tomatoes, insecticides are not effective, so only use them as a last recourse after other methods have been tried.
What can I say? Unfortunately, this species is just one of “those guys” who cannot get along with most crops. They are a huge agricultural and economical pest, and control is very much warranted.