How to Get Rid of Tomato Hornworms
Though not as rampant or widespread as smaller swarming pests, tomato hornworms are almost ubiquitous with gardening as they are easily one of the most recognizable insects of the season.
Like all caterpillars, tomato hornworms are not fully formed adults but are merely the transitional larvae prior to the hornworm maturing into a fully-formed five-spotted hawk moth. Because tomato hornworms are a young and developing larvae, they feed quicker and more aggressively than just about any mature insect in the garden.
Tomato hornworm is nearly identical to the tobacco hornworm in both color and size, as each can be found almost exclusively on tomato plants and occasionally other members of Solanaceae such as eggplant, pepper, potato, and tobacco. While other foliage-eating insects only consume the softest plant tissue, tomato hornworms are far more ravenous and will feed on the most fibrous parts of the plant.
What Is A Tomato Hornworm?
What Do Tomato Hornworms Look Like?
Both tomato and tobacco hornworms are nearly indistinguishable from one another at a first glance as each are about 3-4” long with vibrant green caterpillar bodies.
Though some can be found with dark amber-colored bodies, most tobacco hornworms will be bright exotic green and will all have a pattern of exactly seven white lines marking the length of their body. These white lines have an accompanying black line on tomato hornworms and a green line for tobacco hornworms.
Tomato hornworms have a sharp and distinct tail spine referred to as the “horn” which often confuses gardeners as to which end is which, likely influenced by the thought of the horned rhinoceros or narwhal.
Tomato Hornworm Damage
Don’t let the name confuse you because hornworms do not bury in tomatoes like worms, but are true caterpillars that feed directly on the exterior of the fruit.
What Do Tomato Hornworms Eat?
Tomato hornworms and tobacco hornworms are often confused for one another as they both exclusively feed on crops within the family Solanaceae (nightshade) such as tomato, eggplant, pepper, and tobacco.
Though large and 3-4” long, both types of hornworms are still young maturing larvae that must consistently feed before transitioning into an adult moth.
Whether a tomato or tobacco hornworm, tomato plants of any kind are the crop of choice for both of these species of caterpillar, as they’re known to quickly and aggressively consume the entire host, including foliage that even the most ravenous infestations won’t consume. Tomato hornworms are not commonly found on eggplant or pepper plants if there are available tomato hosts in the local area.
Tomato Hornworm Eggs
How to Get Rid of Tomato Hornworms
Tomato hornworms are some of the largest pests in the garden and can’t be eradicated in the same manner as smaller aphids or spider mites.
Hornworms are solitary caterpillars that do not swarm and can be removed individually by hand. For a larger hornworm population, try the store-bought bacterial gardening powder Bacillus thuringiensis, or simply known as Bt. The bacteria is non-toxic to humans and animals but very effective when consumed by caterpillars.
There are several types of Bt for different insects but, if eradicating hornworms and caterpillars, be sure to only use Bacillus thuringiensis var. kurstaki.
Maintaining an active birdfeeder is one of the most organic means to keep your garden free of hornworms and caterpillars, since visiting birds will naturally check your garden soil for grubs and insects.