The Adventures of a Tomato Hornworm

One cool and crisp late October day last year, my kids and I were ripping out what was left of our tomato plants. You would think this would be an easy task, but our tomato plants did exceptionally well last year and those roots ran pretty deep! So, as I was yanking and tugging at those stubborn plants, my kids were running around the yard and looking at all the plants that were already pulled out. One of the kids saw a caterpillar-like wormy thing (I believe that is the scientific name for it!) on the tomato plant and showed it to me. Of course this made us wonder what it was, so off to the internet we went! We found that this was a Tomato Hornworm. The reason this caterpillar is referred to as the Hornworm is because of the "horn" that is located on its rear end. According to Wikipedia, the Hornworm feeds off of the tomato plant, but is not particularly fond of marigolds. Since these creatures are not very helpful to anyone's garden, I think investing in a couple of marigolds to plant around tomato plants would be a good investment! The caterpillar eventually turns into the Five-spotted Hawkmoth. We happen to have a book about butterflies and moths (A Golden Junior Guide - Butterflies and Moths), so we found that a Five-spotted hawkmoth is a type of Sphinx moth that is referred to as Hawkmoth because of its ability to fly up to 35 miles an hour! That's pretty fast for a little moth!

We took the Hornworm and put it in a bug catcher to study it further. We also gave the caterpillar some tomato plant and leaves along with some green tomatoes for food. This little guy lived in our bug catcher for 2 weeks! The problem was that these Hornworms have a natural enemy that preys on them. It's called a parasitic Braconid Wasp. It's "parasitic", which means that it lives off of another creature. A wasp had stung this Hornworm and laid its eggs inside of it. The eggs hatch into baby wasps (larvae) and they live off of the Hornworm, literally eating it alive! Gross, I know. It's like something out of a science fiction movie! The larvae the formed cocoons on the Hornworm. You can see the cocoons that the the larvae formed here. The new wasps eventually emerge from the cocoons and they will help to keep the other Hornworms from ruining your garden! The wasps leave what is left of the Hornworm's body and fly off. Unfortunately, the wasps that hatched from the Hornworm's cocoons that we had did not make it through the cold weather. But if you see a Hornworm with those white spikes sticking out of its back, it's best to leave it alone because the wasps will kill off the Hornworm and also any other Hornworms they find. That way, you can still enjoy your tomatoes without having to worry about any caterpillars eating your garden clean!

The photos I included through the links are not my own. We didn't even think about getting photos of our Hornworm. I guess we were just so amazed at all that was happening that we completely forgot! I ended up taking the Hornworm and its "guests" (the parasitic wasps) in the bug catcher to my kids' school to show it off and tell them about it. They thought it was pretty "cool" and enjoyed learning about it. 

We really enjoyed learning about our Hornworm and now we know that it isn't something we want in our garden. I think I will take more of those parasitic Braconid Wasps instead. They will keep our garden healthy and safe from some pests. Next time you eat a tomato, you can thank a wasp for doing its job so well!

Cheryl