Hornworms are large, ominous looking insects that love to feed on tobacco and tomao family crops. They can grow up to 5 inches long and have a hor” on one end. The horn wont sting you, but these insects can devour the foliage of tomatoes, nicotiana, moonflowers, potatoes, eggplants, and peppers. There are two common hornworms – tomato and tobacco. They look similar except for some striping and coloring, and both love any plant in the Solanaceous family.
The adult hornworm is a large, brown hawk moth that lays eggs on the undersides of leaves. Some call them hummingbird moths because they flit around the garden, enjoying the nectar from many flowers. After the eggs hatch, the green larvae begin to consume leaves, and sometimes green fruits, at an alarming rate. The caterpillars eat and grow for three to four weeks before pupating in the soil. In Southern regions there may be two generations a year, while in the North there is usually only one.
Because of their size and appetite, hornworms can quickly strip the foliage off branches. You usually see the damage before you see the insects because their coloring camouflages them well. If you catch them early enough, little permanent damage will be done to your plants. You can control these voracious eaters by handpicking individual caterpillars and dropping them in a pail of soapy water or feeding them to chickens. For large infestations, spray Bacillus thuringiensis kurstaki. This organic biological spray can be found under the name of Dipel or Thuricide. It is the same spray you’d use on cabbageworms, and it is safe for pets, kids, and the environment. However, it kills all larvae in this family of insects, including swallowtail butterfly larvae, so be careful where you spray it in the garden. If you see a hornworm with white egg sacks on its back, leave that hornworm in the garden. The egg sacks are from the braconid wasp, which will parasitize and kill hornworms in your garden.