Tomato worms are one of nature’s two most popular types of hornworms. The other is the tobacco worm. The scientific name for tomato worms or the “tomato hornworm” is Manduca quinquemaculata. While tomato worms are not considered harmful to humans, they are extremely harmful to plants, vegetables, and landscaping. Tomato worms appetites’ are extremely healthy, so they will nosh on your tomatoes, leaves, and fruits for hours and hours on end if you allow them to. In addition to tomatoes, tobacco and tomato hornworms are also attracted to eggplant, potato, and pepper.
Adult tomato worms are typically 3 to 5 inches long and they have a large black horn on their rear ends. This horn may look like it can do plenty of damage, but its actually pretty harmless. If you suspect that a tomato worm has bitten you, chances are it wasn’t a hornworm that bit you. A tomato hornworm (or any hornworm or insect for that matter) will do whatever it can to protect itself – especially if you handle it for too long. However, it doesn’t defend itself by “biting.” A hornworm will spit out the contents of its stomach, it will wiggle and thrash about, and it may even wrap itself around your finger, but it does not have the capability to sting or pierce the skin. It is important to keep in mind, however, that the hornworms’ “wrap” can be quite uncomfortable, so it’s best not to handle them for too long.
Another issue with handling tomato worms for too long has to do with parasite infestations. While the tomato worm may be infected by a number of parasites, the most common is the braconid wasp. The larva hatch on the tomato worm and it feeds on the worm’s insides until the wasp is ready to hatch. The cocoons are quite visible to the naked eye and they look like raised white bumps on the tomato worms body. It’s probably not a good idea to handle a tomato worm that shows signs of a parasite infestation, but leaving it in your garden can be a good thing. Once the wasps emerge from their cocoons, they will kill the tomato worm host then seek out other tomato worms to infest. This natural enemy is an effective treatment for tomato worm infestations.
If you have a small garden and if you don’t notice white protrusions on any tomato worms that you see, it’s ok to quickly handpick the tomato worms from your garden. You can drop them in a bucket of water or snip them in half. This is considered an effective method of tomato worm control in small gardens. Other effective methods of controlling tomato worms in your garden include: rototilling and biological treatment. Rototilling means to turn up the soil after harvest. This will destroy any pupae that may be there. Biological treatment with Bacillus thuringensis, or BT (e.g., Dipel, Thuricide), will kill the tomato worms and it is especially effective on smaller larvae. BT must be used with extreme caution because it can be harmful to humans.
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