Can tomato fruit worms come from a corn field? - Ask Extension
We have tomato fruit worms destroying our tomatoes. I readcthat tomato fruit worms and corn ear worms are the same? We live across the street from a l...
Knowledgebase
Can tomato fruit worms come from a corn field? #912224
Asked July 31, 2025, 5:50 PM EDT
We have tomato fruit worms destroying our tomatoes. I readcthat tomato fruit worms and corn ear worms are the same? We live across the street from a large cornfield. Is it possible that the cornfield is the source of the moth/tomato fruit worms?
Carroll County Maryland
Expert Response
The caterpillars pictured look like Yellow-striped Armyworms and not Tomato Fruitworms/Corn Earworms. Even so, the adult female moth that laid eggs in a corn field could also have flown into a yard nearby and done the same.
The diet of Yellow-striped Armyworms is broad, and while they don't overwinter this far north, they can arrive (as adult moths that are laying eggs) as weather fronts carry them north from the Gulf states during summer. The colors can vary a bit on the caterpillar's body, as can some of its patterning, but the yellow "shoulder" stripes are often consistent.
If needed, one treatment option is to spray a low-toxicity insecticide like one containing the active ingredient spinosad (Bt will probably not work on caterpillars this mature), though that might risk harm to pollinators if any are visiting open flowers that are contaminated with spray. A topical spray like horticultural oil or insecticidal soap might suffice instead to control the caterpillars, but it must be sprayed directly on the pest for it to work, and at that point, it would be faster and cheaper to just pick them off by hand since you'd have the caterpillars in sight. In comparison, spinosad soaks into the tissues on which it was sprayed, so as caterpillars chew into it, they are poisoned.
If you opt to use a pesticide, follow all product label directions, and make sure it's a formulation labeled for use on edible plants. There may be a delay needed between when a spray is applied and when the fruit can be harvested, which will be noted in the label directions if it's applicable. (This may be called a "pre-harvest interval.")
Miri
The diet of Yellow-striped Armyworms is broad, and while they don't overwinter this far north, they can arrive (as adult moths that are laying eggs) as weather fronts carry them north from the Gulf states during summer. The colors can vary a bit on the caterpillar's body, as can some of its patterning, but the yellow "shoulder" stripes are often consistent.
If needed, one treatment option is to spray a low-toxicity insecticide like one containing the active ingredient spinosad (Bt will probably not work on caterpillars this mature), though that might risk harm to pollinators if any are visiting open flowers that are contaminated with spray. A topical spray like horticultural oil or insecticidal soap might suffice instead to control the caterpillars, but it must be sprayed directly on the pest for it to work, and at that point, it would be faster and cheaper to just pick them off by hand since you'd have the caterpillars in sight. In comparison, spinosad soaks into the tissues on which it was sprayed, so as caterpillars chew into it, they are poisoned.
If you opt to use a pesticide, follow all product label directions, and make sure it's a formulation labeled for use on edible plants. There may be a delay needed between when a spray is applied and when the fruit can be harvested, which will be noted in the label directions if it's applicable. (This may be called a "pre-harvest interval.")
Miri
