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It's a Bug-Eat-Bug World: Controlling Tomato Hornworms with Braconidae Wasps

The Green Invader is coming. During the first two years of growing my red delicious orbs I would declare war when the first hornworm of the season showed its extended green self in one of my prized heirloom tomato plants.

I would gladly give it a swim in a special glass jar with a water and soap mixture for offending bugs. I called this my Swimming Pool of Death. Dozens of Japanese beetles and a few hornworms went for a dip in this noxious fluid never to decorate and defile a tomato plant again.

 hornworm

Hornworm with wasp eggs

Tomato Hornworms and Their Natural Enemy

One day when I was researching the University of Maryland’s Grow-It-Eat-It website’s insect section, I learned many things about bugs. Hornworms eat more than tomato plants. They also will eat other plants from the solanaceae family like eggplant, peppers, moonflower, tobacco, and potato plants.

I came across a photo of a hornworm with a pearly-white adornment on its back. I had seen a couple of these types of hornworms and plunged them in the pool of death despite their wearing attractive pearly jewelry. What a mistake I had been making. Those pearly white bits of hornworm jewelry were Braconidae Wasp eggs.

This specialized wasp of Lilliputian stature can bring down the dreaded hornworm on a slow road to death. Considered a friend of the tomato grower it’s a mere half inch or so in length and while deadly to the hornworm it’s harmless to humans. Once I figured this out I’d let the Braconidae eggs go through their dance steps on the backs of hapless hornworms. The little wasps go through the pupate stage into the cool looking white egg sacs we see. Later on they feed on their host until ready to fly away and search for more yummy hornworms. The end result is a dead hornworm and several happy little wasps. What a cool little winged critter those wasps are.

But Wait, a Stay of Execution Has Been Granted

I figured I’d be a hornworm hater forever until visiting the master gardener table at the Baltimore Farmer’s market this spring. I love to chat with those experts of massive plant and garden knowledge and usually have a question or three. On this occasion, I spoke of my dislike for hornworms and the master gardener said hornworms need love, too.

It turns out if hornworms dodge Braconidae Wasps and crazed tomato growers like me they morph into a lovely Sphinx Moth. Because I love butterflies and most large moths I decided it wasn’t too late for me to show a little compassion for one of Mother Nature’s pieces of the puzzle we humans haven’t figured out. So starting this year when I found hornworms in my prized tomatoes I would pluck off about eight inches of tomato branch and give the hornworm a ride to the nearest maple tree where they could ponder their choice of tomato patch.

 very large Juliet

A very happy 'Juliet' tomato plant

Now that I’m a recovering hornworm hater/killer I must be accumulating Karma points, good for who knows what. Perhaps a Sphinx Moth will show up on a day when I need a bit of good cheer and I can say, “I probably saved your life so you could go forth and repeat the cycle.”

Maybe you, too, can show some compassion and save one or two? If not there’s always the swimming pool of death. Your tomato plant will be spared and you won’t go to jail for killing a hornworm. That’s almost a happy ending.

tomatoes from my garden

Kurt Jacobsohas been a chef for 40 years and, after being schooled in the U.S. Coast Guard, he trained in many restaurants under both kind and maniac chefs. Kurt is starting his fourth year of container and raised-bed organic gardening and is volunteering at Wilbur’s Farm in Kingsville, Maryland, to learn real organic gardening. For this and other recipes using garden greens, and more fresh veggies check out his food blog. For tasty travel ideas check out Kurt's travel blog, TasteofTravel2.com. Read all of Kurt's MOTHER EARTH NEWS posts here


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