Green Caterpillars

A Handy Guide to Green Caterpillars

Have you ever noticed green caterpillars in your garden, munching on your veggies or flowers? If so, you have probably wondered what exactly they are. This may seem simple, but actually, there are more than one type of green caterpillar. In fact, there is nothing called a 'green caterpillar'- there are just caterpillars that are green. Does that make sense? If not, then it will after this article explains to you a few common green caterpillars that you may see in your yard.

First, let us talk about what a caterpillar is. If you remember your grade-school education (and if you do not, don't worry; most people don't), then you know that a caterpillar is actually a creature that turns into another one through a unique process called metamorphosis. During this process, the creature starts off as a larva. For a moth or butterfly, a caterpillar is the larva. Following this, they enter into a stage of inactivity called the pupa stage (usually involving a cocoon). Then, during chrysalis, the pupa transforms into a moth or butterfly. Thus, caterpillars will eventually become other, larger insects.

Now that we have reviewed what a caterpillar is, we can discuss green caterpillars. The first that most often comes to mind when people say a green caterpillar, or when people see one in their garden, is called the tomato hornworm (or Manduca sexta). The tomato hornworm is green, about 3 to 4 inches long, and has a red horn on the head (hence the name). They also have eight, white, V-shaped markings on the body, which allows quick and easy physical identification. These caterpillars are found throughout most of North America, specifically the northern United States, and regularly feast on vegetation, including tomatoes. This lust for tomatoes gives the tomato hornworm its name.

Farmers despise this green caterpillar because of how much destruction it can cause by eating the leaves and fruit of tomato plants everywhere. The hornworm is capable of eating many times its weight on a weekly basis, and since it multiplies fairly easily, this can spell trouble for anyone growing tomatoes or really any other related crop in a garden or on a farm.  For small gardens, picking these pests off by hand can be effective – but if a small white “nest” appears on it, leave it alone. This houses a baby wasp that will eventually kill the bug. For larger gardens or farms, multiple pesticides are effective. The tobacco hornworm is very closely related to the tomato hornworm, except it has seven white slashes on its body.

The next of the green caterpillars that often shows up is called a currant worm. This worm – the larval form of the sawfly – actually isn't a caterpillar at all, but is a worm larva of a fly (caterpillars are larvae of moths and butterflies). But, most people assume that it is a caterpillar, so we will talk about it in detail. The currant worm is quite small and slender, and can have black circular markings along its sides which makes it identifiable.  It is still hard to find these worms, though, unless you are deliberately looking for them – and that is probably only after you observe damage on your plants. The currant worm may be small, but it is quite formidable. It usually munches on berry plants and currant plants, but can be found on other plants if you have a diverse garden or farm. A plant can be defoliated and stripped of its leaves, fruits, and flowers in as little as two or three days, depending on how many currant worms are on it. So, if you see these pests, remove them or put insecticide on them as soon as possible.

In short, if you see any of these green caterpillars, you should assume that they can damage your plants. Therefore, it is best to deal with them as soon as you can.