Tobacco Hornworms

Yep, you read that right. Tobacco Hornworms. This isn't a craft project per se, but a cool science experiment the Miniature Master Gardener (MMG) and I did just for fun (and counted as part of her homeschool science curriculum). It's a long story, so settle in with a cup of hot tea and enjoy!

The Mysterious Origin of our Tomato Plants

Let's go back to the very beginning. Two summers ago, we had the brilliant idea to start a compost bin. We set an old MDF dresser on its side (without the drawers) and chucked in all our compost ingredients. The bin went well until the MDF started to fall apart and we noticed mice were drawn to it. So we carefully moved the compost bin and contents to the opposite corner of the yard, away from the house. It remained there for a while, but we started seeing snake skins and bunny droppings around it. Finally, we gave up on the rotting dresser. However, my brilliant husband, an avid Pinterest user, has found several ideas and hopes to build me a new and improved compost bin sometime in the future.

The original site of the compost bin has yielded some very fun mystery plants. We had a cantaloupe vine grow out of there which yielded just one cantaloupe, but the best cantaloupe I've ever had. We had an avocado tree sprout, but the two-year-old pulled all the leaves off of it. We have a new tree that I think is a peach tree. And we had 4 tomato plants grow from there. Two we transplanted to our official "garden" area, and two we left growing in the five-foot-wide space between the fence and the house.

The Finding of the Caterpillars

The two tomato plants in the garden seemed to be doing much better than the ones we left by the house. Imagine my surprise when I found two of these big, intimidating caterpillars on the upper leaves!

We looked them up on the computer and found out many things. Most tomato farmers consider them pests and advise quickly dunking them into a cup full of soapy water (in case you have some or too many of these beauties you need to make disappear, that's what I recommend). Often these caterpillars play host to a parasitic wasp and some sites recommended keeping the caterpillars infected with the wasps alive long enough to allow the wasps to hatch and infect more. Other websites claimed to plant tomato plants in the hopes of attracting the hornworms.

From what I could tell, these are tobacco hornworms, which are very similar to tomato hornworms. Both feed on tomato and tobacco plants. The spike, while menacing, is a fake.

Caterpillar Adoption

Caterpillars in the Jar

So we rounded up the first two, plus a third one,  and put them in a large pickle jar. They need plenty of soil for burrowing, since these caterpillars make their cocoons underground. We also put in a sponge and lots of fresh green tomato stems and leaves. It was really neat to watch them munch away on the leaves. The girls were able to use magnifying glasses to see the caterpillars' eyes and mouth.

Big Fat Caterpillar

At first, they didn't seem to eat much. In just a few short days, they were eating a whole jar's worth of leaves within a few hours. I hoped my poor tomato plants would be able to keep up with them. The caterpillars grew fat, as large around as my thumb, and twice as long. I'm not exaggerating! Look them up for some pictures on how gigantic they get. The picture at right is not quite their full size.

Remnants of a Cocoon

Burrow

Then one by one, they lost  interest in the leaves and started doing "laps" on the dirt at the bottom of the jar. They slowly burrowed into the soil. One burrowed pretty close to the glass, so we could see when her cocoon formed. For a long time, nothing happened. I had to remove the remaining leaves because they started to rot. We set November 1st as their eviction day if nothing happened.

Sphinx Moths

(Or Hawk Moths) As I was passing by the jar a couple days ago, I noticed the surface of the dirt was not smooth like usual. There was something on it. I looked closer and found a large moth lying on its back with its legs in the air. We took the jar outside and gathered up some more foliage from the tomato plants (which were thriving again by this time). It was a little bit of a struggle for the moth to get on the plant, but once she did, she scurried quickly to a spot where she could hang. Her wings were shriveled, but a few hours later, she had long brown mottled wings that were straight.

"Liz" getting cozy on the leaves

Soon after, the second moth emerged. She moved up the leaves more quickly and got in to Liz's spot. There was some fluttering as the two moths sorted out who was going to hang where. That attracted the attention of my cat (since these moths are huge, look like bats, and are often confused for hummingbirds) and merited the jar being shut up in the bathroom for the night.

By the next morning, the third moth had emerged and the first two had straightened their wings. It was time to say goodbye.

 We planned some time at the end of our school day to walk to the wilderness area near our house and drop off the moths (same place we released a turtle that wandered into our yard). We picked the same spot as the turtle: just on the edge of the pond, under a tree. After a few solemn words, the gardener pulled the masking tape off the lid. Instead of a massive fluttering of wings, Liz flopped out onto the ground after getting her foot stuck in the tape and crawled really quickly toward me. I imagine she thought I was some sort of tree. We got a stick and convinced her to grab onto that while we moved her to the tree. As soon as we put her on the trunk, she crawled to the edge and clung to the side with her wings folded around her.

Notice the bright body spots.

Perfect Camoflauge

The second moth, "C" climbed onto her stick after we showed it to her. Mini Master Gardener (okay, I've got to come up with a better nickname for her), actually got to hold the stick. C pretty much stayed like the below picture once she got on the tree. 

 Since "E", the last moth, was snacking on a tomato flower and had the most fragile wings, we moved her and the foliage at the same time.

 Our caterpillars turned out to be really fun. Mini Master Gardener is already hoping for some new ones in the spring.

Shared on Friday's Nature Table at The Magic Onions: http://www.themagiconions.com/2012/11/fridays-nature-table-7.html