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The garden glutton

Beware of hungry hornworms in your tomato patch. They have an amazing appetite!

Tomato hornworm larvaParents of teenagers often say “My kids are eating me out of house and home. I can’t believe how much they eat.”

Just be glad you are not feeding a hornworm. They eat FOUR TIMES their weight EVERY DAY!

Imagine if your 150-pound teenage boy had the appetite of a hornworm and you took him to McDonalds. He would step up to the counter and order 600 Big Macs. Not 6 Big Macs; 600! That’s what I call a Big Mac Attack!

He is just getting started. Next comes 600 large orders of French fries! Add to this 100 side salads! After all, he must have a balanced diet.

For dessert, how about 100 ice cream cones? Fortunately, they offer reduced-fat ice cream.

We have to get tomatoes into this hornworm diet, so let’s add 1,000 packets of ketchup to slurp on!

 It’s hard to eat four times your weight in one day. And tomorrow he will eat even more!

Tomato and tobacco hornworms (Manduca spp.) are amazing insects. Parasitized tomato hornwormTheir genus Manduca literally means glutton. The four-inch caterpillars eat so much their guts literally burst out of their skins, requiring them to molt and shed their skins several times. They increase in size by 1,000 times in only three weeks. That’s comparable to a cat growing to the size of an elephant!

The striped patterns of the hornworm allow them to camouflage themselves within the vines (top photo). Most gardeners don’t realize a hornworm is in their garden until a tomato branch disappears overnight. Hornworms will also eat other members of the tomato family, including potato, pepper and nicotiana.

Once you notice one, a hornworm is easy to control. Grab it and throw it in a bucket of soapy water—or throw it on the ground and stomp on its guts. Gross, but effective.

While picking off hornworms, you may notice one covered with white cocoons. This hornworm was attacked by a parasitic wasp. The wasp laid her eggs inside the hornworm. Wasp larvae hatched inside the caterpillar and ate the guts out of it. What a way to die! Just like an Aliens movie! Once done feeding, each larva will spin a cocoon to pupate inside. After resting, it emerges out of the cocoon as an adult wasp (bottom photo). Nature is cool!


Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Published in the NDSU Yard & Garden Report, September 1, 2014. Photos were made available under Creative Commons licenses specified by the photographers: Chris Bedeand Paul VanDerWerf.


McDonald’s. 2014. McDonald’s USA nutrition facts for popular menu items. www.nutrition.mcdonalds.com/getnutrition/nutritionfacts.pdf. Accessed 8/30/2014.

Moeller, K. 2014. ASU Ask A Biologist. https://askabiologist.asu.edu/manduca/introduction/. Accessed 8/30/2014. Arizona State University: Tempe.

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