Hornworm Experiment - Garden Fun for Kids

This post may contain affiliate links. See my disclosure.

Each summer we pick through our tomato and pepper plants looking for hornworms. These are common garden pests that love to devour tomato and pepper leaves. Their camouflage is frustratingly good so they can be tricky to spot. They can work their way through your plant very quickly so you have to stay on top of finding them! One year I was talking with my kids about how these little destructive creatures turn into huge moths. That, of course, led to them wanting to see that lifecycle change happen. A new tradition was born! Here’s a fun garden activity for kids with hornworms!

How to Find Hornworms in Your Garden

Tomatoes and peppers are their favorite plants to munch. Try to head out to to your garden to hunt for them most days. They can strip your plant of leaves very quickly so it’s important to keep on top of this task. Their camouflage stripes help them blend in perfectly with the underside of tomato leaves. They look like a slightly curl leaf. When you start seeing heathy leaves that are damaged and eaten, you’ll know you have a hornworm to find. You can also spot their area when you start to see their poop on leaves. It’s tiny brown pellets kind of shaped and ridged like pineapple.

If you want to do with gardening activity with hornworms but you can’t find any, ask a local gardener or someone who raised chickens. Chickens love to eat hornworms, so people often collect them from gardeners to feed their chickens.

Close up of huge tobacco hornworm

Gardening Activity with Hornworms

Introducing my buddy…

This is actually a tobacco hornworm. It has 7 diagonal strips and a red horn. No, I’m not growing tobacco…these guys feed on tomatoes as well. Here’s a great video that describes the two big differences between tomato and tobacco hornworms. For this gardening activity, it doesn’t matter which one you have.

This guy was huge! We put it in a bug catcher cup with a magnifying glass top so my kids could see it up close. I was thinking it would be a great way for them to look at it while drawing it in their natural journals. However, the girls had something else in mind. They wanted it to put it in our butterfly habitat and let it turn into a moth. Um…no. These guys can destroy a tomato or pepper plant seemingly overnight. As a gardener, it made me just cringe to think we were going to help it complete its lifecycle. But how could I say no to the girls wanting to see this? I’ll admit I was a little curious too. Just a little…

The Things We Do for Our Kids…

The next day I went out to cut some fresh tomato leaves to feed the little pest, but it didn’t seem at all hungry. I put a container of garden soil in the butterfly habitat so that it could burrow down to pupate. Just a few minutes later, it headed under. Luckily, I saw it at the last minute and we managed to watch it’s tail disappear.

Hornworm burrowing to pupate

Tick Tock, Tick Tock

Several weeks later, the sphinx moth emerged! It happened so quickly. The wings were still wet and shriveled. We watched over the next hour as they dried and expanded. We were really surprised that it was so big! We let it go the next night and watched it fly off – hoping that it wouldn’t return to our garden. It was actually quite beautiful!

Tobacco Hornworm Sphynx Moth

They are excited to find more and continue to hatch them. I’m glad we were able to experience it, but I think I prefer giving them hot soapy baths. The things we do in the name of science and nature for our kids. Sigh…

PS. I apologize to all the gardeners out there who battle these nasty guys every year.

Please don’t tell my gardening buddies that we did this. Please?!