Welcome to the thirty-second issue of Stalking Mike Blair Outdoors. I hope you are enjoying your summer because fall is quickly approaching! Soon we’ll say goodbye to the sweltering heat and green views. It will be replaced with cool breezes and warm colors. Nature has many different states, there are beautiful and desirable aspects to them all.
You may have seen these odd creatures in your garden this summer. You or your child may have even caught one as a pet at some point. There are two types of popular hornworms: the Tobacco Hornworm and the Tomato Hornworm. They are also commonly called the Goliath worm; this is probably because of their large size. They are relatively large insects that can measure up to four inches. However, despite their large size, they can be difficult to see because of their protective coloring.
Hornworms feed on the foliage of various plants, including the tobacco and tomato plant. The damage to plants can occur in midsummer and can continue well into the remainder of the growing season. They don’t like the heat of sunlight, so they keep to the inner areas of the plant, in the shade, during the heat of the day. They’ll move to the outside of the plant near dusk. Even with this tactic, you can find them most often on the underside of the foliage.
The differences between Tobacco Hornworms and Tomato Hornworms are mostly in their appearances. The Tobacco Hornworm has seven diagonal lines on its sides. These are straight white lines with black margins. The Tobacco Hornworm has a curved red horn. The Tomato Hornworm has eight V-shaped markings. These markings have green margins. These insects have a straighter blue-black horn. An easy way to remember the difference is in the markings. Tobacco Hornworms have straight lines like cigarettes. Tomato Hornworms have V-shaped markings as in “vine-ripened tomatoes.”
The hornworm has a short life cycle of about 30 – 50 days. In most areas you get two generations of hornworms per year. However, in Florida you can see up to three or four generations per year. The eggs are spherical in nature, are approximately 1.5 millimeters in diameter and are a translucent green. They hatch two to four days after they are laid.
Hornworms, both tobacco and tomato have a rare ability to metabolize the nicotine that’s found in the tobacco plant. This nicotine is poisonous to most animals. These insects take advantage of that fact and use it as a defense mechanism. The smell they emit from the nicotine deters spiders and other predators from making a meal of them; this is called toxic halitosis. If this doesn’t work the hornworm will produce a loud clicking sound when it’s attacked. This clicking sound warns the predator that eating them will not be pleasant.
Hornworms are actually the larvae stage of a moth. After the pupae stage they are a Sphinx moth. The only difference you can tell between the tobacco and tomato then is by the spots on the moth. The adult form of the tobacco hornworm has six orange spots while the tomato hornworm adult has five orange spots.
If you see these insects in your vegetable garden, you may want to relocate them to a different area to avoid the destruction of your plants, or perhaps you will want to keep it as a temporary pet. They’ll be seen throughout the growing season, but like most insects will disappear for the winter.
Be sure to check out the Hornworm Photo Gallery!