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Tobacco hornworm Manduca sexta
IDENTIFICATION — These 3- to 5-in.-long giants of the caterpillar world have a large harmless spike, or horn, on their tails. Their green color blends into the foliage of tomato and tobacco plants, some of their favorite foods. They will also attack plants in the nightshade family, such as datura, petunia and nicotiana.
DAMAGE — In early to midsummer, caterpillars can quickly strip a plant of foliage and may sometimes even chew on green tomatoes.
CONTROL — If there are just a few caterpillars on your plants, handpick them. If numbers are larger, spray Bt on affected leaves only. Thuricide, which contains the kurstaki strain of Bacillus thuringiensis, works well on tobacco hornworm and is safe to spray right up to harvest, but be sure to wash fruit well before eating. Or grow alyssum, dill or Shasta daisy to attract braconid wasps, which lay dozens of eggs within each larva, parasitizing and killing it.
