ImageWe tomato lovers are particular about growing our favorite edible. We spend the off-season reading about different varieties. We carefully prepare lists, weighing the merits and liabilities of each one. Trades are made on the internet, and orders placed with well-researched companies. Seeds are started in the proper medium, and the seedlings are watched over like toddlers. We study long-range weather forecasts to select just the right moment in time to place our babies in the garden, and we mulch, feed, and hover over the growing plants with a careful eye. Every aphid, stinkbug, and cucumber beetle, is dispatched with a vengeance. No leaf is left unturned, and we are smug in our confidence that our tomatoes are safe from harm.

The sun is shining brightly, and the green tomatoes glow like jade colored jewels on the dark green vines. We survey our potential harvest with glee. All is right within the Tomato Universe until the morning when we find whole leaves missing, blooms stripped, and even our precious tomatoes chewed by some unwelcome villains. What in the world could have caused this much damage in such a short time? We were just here yesterday. This looks like a whole army of tomato chewing thugs invaded overnight and began stripping our plants clean. Those of us, who have dealt with this problem, know that the battle is on. The Attack Of The Tomato Hornworms has begun.

ImageThe Tomato Hornworm is the caterpillar of the Five Spotted Hawk Moth, Manduca quinquemaculata. This caterpillar feeds on plants that belong to the Solanaceae Family, which includes tomatoes, peppers, eggplants, and Brugmansia. The moth is a large, pretty, gray moth, with bright pink markings on its abdomen. It flies in the evening, and at night, and is attracted to night blooming flowers. Many butterfly and moth lovers actually grow plants from this Family to encourage their presence. I do not mind the moths coming to my garden, but when their children set up housekeeping in my tomato patch, I take action. I figure that enough escape my wrath to preserve the species anyway.


Tomato hornworm caterpillars are pale green with white stripes on their abdomen. A fierce looking ‘horn" adorns the rear end. They are slow moving, and blend with tomato foliage perfectly. Usually the first sign of their presence is stripped foliage and blooms. They tend to hide beneath leaves and along interior stems during the day, becoming active, and munching their way through your tomato patch during the cooler evening hours.

These caterpillars start out as small, inconspicuous green worms that look like they could never lay waste to a whole tomato plant. They quickly consume all available greenery, and become voracious monsters that can exceed three inches in length. They are hard to locate on the foliage, as they are masters of camouflage. Many gardeners give up, and simply delude themselves into thinking that the hornworms have moved on to greener pastures. If you are one of the gardeners who believe that, I have some blue tulip bulbs to sell you!Image

The best way to locate tomato hornworms on your plants is to follow the frass. Now for those of you who do not know what frass is, it is simple. What goes in the front end of a tomato hornworm eventually comes out the back end. Frass is simply caterpillar poop. Little caterpillars make little frass, big caterpillars make big frass. These are big caterpillars. You may even think that a herd of bunnies has taken a liking to tomato plants. The ruler in the picture is just to show how much frass a three-inch hornworm can generate. It should not be hard to find the one that produced this stuff!

ImageWhen hornworms attack, you have a few options in controlling them. You can hand pick them into a bucket of soapy water, you can do the "drop and stomp," or you can spray your plants with Bt. Bt is short for Bacillus thuringiensis. It is a live bacteria that is deadly to caterpillars and nothing else. Considered perfectly safe for the Organic growers, and effective enough, that the people who prefer chemicals have no argument using it either. When mixed according to directions and sprayed on tomato plants, Bt will eliminate any hornworm that takes a bite of your precious tomato plants. The one downfall to Bt is that it washes off in the rain, so it has to be reapplied after each shower. It is only deadly to caterpillars, and will not harm beneficial insects or humans who consume the vegetables.

Sometimes hornworms are found with oval, white egg-like things hanging on them. In a previous article about garden pests, I explained that these were the pupae of a small wasp that use the hornworm as a host. The eggs are laid inside the hornworm, and the larvae hatch inside its body. They live in their unwitting host, and feed on the soft body parts inside of it. By the time that they pupate on the outside of the hornworm, it is already dead. It just does not know it yet. If hornworms are found on your tomato plants in this condition, leave them be. They can no longer eat enough to hurt anything.

Finding your precious tomato plants stripped of foliage and flowers is a gut sinking feeling. After all of the care and planning that went into making everything just perfect, these thugs invade your domain, and lay waste to all you have worked on. Knowing what they are, and how to deal with them, is the biggest part of the battle. The Attack Of The Tomato Hornworms can be a war that is easily won. Pay attention to your garden. Keep an eye out for these invaders. Prompt elimination will save your tomato harvest.