There is little that compares to the flavor of a vine-ripened tomato. But insect damage to the fruit will definitely reduce the experience. Two groups of late-season pests are common and frequently need to be managed. The first group is caterpillars, which chew small to large holes in fruit using chewing mouthparts. The other group is stink bugs, which cause discolored tough areas under fruit skin using piercing-sucking mouthparts.
Common caterpillars attacking tomatoes in Kentucky include yellowstriped armyworm, tomato fruit worm (a.k.a. corn earworm), and hornworms. Of these, the yellowstriped armyworm has been the most common over the past several years.
The presence of holes in fruit or pelleted frass on the ground are indications for need to manage caterpillars. There are many insecticides available, including OMRI-approved organic materials.
Stink bug and leaf-footed bug damage may be the most common insect injury to tomatoes in Kentucky. Several species contribute to this; brown stink bugs (three species complex) are the most common. Green stink bug and brown marmorated stink bug also contribute to this damage. The damage can begin long before tomatoes are ripe.
Stink bugs pierce fruit skins with their mouthparts and inject enzymes to enable them to feed on fruit. This causes hard corky areas to form under fruit skins, which do not color properly.
These injuries are called ‘cloud spots.’ While there are fewer insecticide alternatives for stink bugs, there are products that provide effective control listed in ID-36.
Ric Bessin, Extension Entomologist