Tomato Hornworms are a very common pest that gardeners have to deal with regularly. These pests can decimate an entire crop quickly if they are not kept under control. Even though they are referred to as the Tomato Hornworm, they attack other similar plants in the nightshade family (Solanaceae), including potato, and tobacco.
Last year I wrote an article about organic solutions for controlling caterpillars and hornworms, but that should be used as a last resort in controlling them. Anytime we are trying to garden organically, we should use the least invasive technique possible to achieve the desired pest and disease control results.
While Bacillus Thuringiensis, otherwise known as BT, is a completely organic and natural pest control measure, there is also an expense to consider in purchasing it which must be taken into account. It also does not specifically target tomato hornworms, but kills all caterpillars, including those who become Monarch butterflies and other butterflies who are very beneficial in our gardens.
With this in mind, the best thing for us to do is to first employ a targeted eradication method first so that we are only getting rid of the actual pests that we are trying to eradicate instead of using a "weapon of mass destruction" to wipe out everything all at once. If you have caterpillars which produce beneficial butterflies who will help to pollinate your garden and produce a larger harvest for you, why would you want to harm them when tomato hornworms are the problem? If other types of caterpillars are found in the garden, they can simply be relocated out of the garden.
Tomatoes hornworms are caterpillars, but they do not produce beautiful butterflies that are going to pollinate your garden, instead, Tomato Hornworms are the caterpillar stage of the 5 Spotted Hawk Moth shown below.
These moths have no benefits to your garden. They have a wingspan of between 4 to 5 inches wide and they have between 5 to sometimes 6 pairs of yellow bands on their abdomen. Adults fly at dusk, and females deposit eggs singly on the upper surface of host plant leaves. The caterpillars are called Tomato Hornworms and each has a black horn at the end of the abdomen. Caterpillars have huge appetites for leaves and fruits and can defoliate plants quickly. Fully-grown caterpillars pupate and overwinter in soil burrows. They can be found from Mexico north throughout most of the United States and occasionally into southern Canada.
The best way to deal with garden pests is by not having the problem in the first place. This can be accomplished by having more healthy microbiology in your soil. The healthier your soil biology is, the healthier your plants will be. The healthier your plants, the more pest and disease resistant they can be.