This Spring I decided to give container gardening a try by planting one tomato and one pepper plant. Things were going well and I had three each of peppers and tomatoes growing nicely. When I stepped onto my deck one morning to check on my darling little plants, I was repulsed to see a giant tomato worm between my two smallest tomatoes. The tomato worm was munching away at both tomatoes and had eaten half of one and a quarter of another. My tomato plant was missing leaves where the tomato worm had eaten them down to stubs. Because I find tomato worms hideous I grabbed a pair of kitchen tongs, pulled him off and flung him into the yard. I’m sure a bird or two thanked me. I began to recall summers as a child where I watched my dad pull tomato worms from his tomato plants each evening. Was there really nothing more I could do to save my tomatoes? Would have to diligently pluck these monster tomato worms from my plants each day?
The tomato worm is actually a tomato hornworm or a tobacco hornworm. The tomato hornworm is the larvae of the Hawk Moth while the tobacco hornworm is the larvae of the Sphinx Moth. Both of the moths are large, grayish insects having a wing span of 4 to 5 inches. Typically the tobacco hornworm lives in the Southern states while the tomato hornworm prefers the north.
The moths lay their eggs on the underside of the leaves of tomato plants. Here the tomato worms hatch and begin to eat away at the leaves on the tomato plant stalk and eventually the fruit that the plant bears. It takes about a month for the tomato worm to pass through its five larval stages. These tomato worms work very quickly while eating. They are busy at night and dislike the sun. Checking tomato (and other nightshade plants) in the evening and early morning hours may reveal tomato worms that couldn’t be seen during the day.
When I began researching way to rid my tomato plants of these annoying tomato thieves, the first piece of advice I found was to simply pluck the tomato worms from the plants before they could do damage. The problem is that by the time they are large enough to easily spot, they have already done their damage. There are a few other safe ways to get rid of tomato worms without using chemicals on the plants, however.
When a tomato worm is spotted, be sure to check it for tiny rice-like eggs attached to its back. These eggs are from braconid wasps. These wasp eggs are a tomato worm parasite. If a tomato worm has these eggs attached to it, it should be left on the plant so that the wasps can complete their life cycle. They will go on to protect other tomato plants from these tomato worms by laying more eggs. Eventually a tomato worm that has broconid wasp eggs attached to it will be consumed and die.
When planting a larger garden where hand picking the tomato worms is not feasible, tilling the soil will destroy the pupae that are laid in the winter months. Bacillus thuringiensis can be sprayed on the plants. This insecticide attacks the digestive system of some insects but is not harmful to humans so using it on tomatoes is safe. Dusting tomato plants with red pepper will help to deter the tomato worms. A mixture of liquid ivory soap, water and vegetable oil may also work to keep tomato worms from wanting to munch on the plants sprayed with such.
There are several safe ways to deter or kill the tomato worms that destroy the foliage and fruit of tomato plants. With a little work any gardener can keep his or her plants healthy and tomato worm free while leaving the tomatoes untouched by chemicals and safe to eat.