Tobacco Hornworm and update with Brachonid Parasites

Tomato Hornworm
Location:  Dayton, OH
August 12, 2010 7:58 pm
My kids found this guy on one of our tomato plants. It ate a huge hole in our biggest tomato. I had to pluck him off and relocate him to a tree at the other side of my yard. Beautiful creature, but I’m sad it ate my biggest tomato!

Tobacco Hornworm

Hi Jessica,
This may not matter much to you, but your caterpillar is not a Tomato Hornworm,
Manduca quinquemaculata, but rather the closely related Tobacco Hornworm, Manduca sexta.  The Caterpillars and adult Hawkmoths of both species look very similar and have similar diets, and both caterpillars will feed on the leaves, and occasionally fruit, of tomatoes.  According to BugGuide the Tobacco Hornworm can be identified by its:  “large green body; dorsal ‘horn’ (usually curved and orange, pink or red) on terminal abdominal segment; up to seven oblique whitish lateral lines, edged with black on upper borders. The similar looking Tomato Hornworm, Manduca quinquemaculata, has eight v-shaped stripes and a straight blue-black horn. These caterpillars are often confused and misidentified.”

We have an interesting personal anecdote to relate.  Our publicist has urged Daniel to create a short 2-3 minute video to use a promotional device for his about to be released book, The Curious World of Bugs.  The video would be used to drum up television appearances including his much dreamed about Martha Stewart spot.  The morning of the video shoot, while he was still trying to settle upon a topic, his neighbor Elena walked by.  She was delivering the caterpillar of a Tomato Hornworm to the child of another neighbor who was raising them to observe metamorphosis.  Daniel knew he had one lurking on one of his tomato plants because of the telltale signs of chewed leaves and green droppings, and he quickly located the culprit.  He was going to give it to Elena to deliver along with her caterpillar, but at the last moment, he decided it would be a nice treat for his Fuzzy Bottom Gals, the new chickens.  Moments after the happy chicks finished fighting over the succulent green caterpillar, Daniel realized he had just fed the ideal topic for the video to the gals, and he decided to walk to the neighbor’s house to borrow the Tomato Hornworm Elena had found.  He returned with the caterpillar in a plastic produce box and sat to write the bullet points for the video monologue, not wanting to place the Tomato Hornworm on the plant too early since they are so well camouflaged and he wanted to be able to place it where the camera could easily include it.  About a half an hour before the video shoot, Daniel discovered that the Tomato Hornworm had escaped and it was nowhere to be found, so two different caterpillar subjects evaded a video appearance.  Undaunted, Daniel did the video without the subject actually appearing.  Hopefully he will be bright, witty and charming enough to entice the producers of the Martha Stewart Show to consider him for a guest appearance, even without a caterpillar.  Daniel still has to inform the little girl up the street, Milo, that her Tomato Hornworm is an escape artist.

Update on the Tobacco Hornworm:  Parasitized by Braconid Wasp!!!
What a great story! I hope the little girl wasn’t upset about her caterpillar. Sad update though, it has since died. We decided after my first email to keep it and hope for the best. Fed it many fresh tomato leaves and thought things were going well. It got lethargic so I sat the critter carrier we bought for him outside in the sunlight and hoped the warmth would help him. The next day, my daughter came running in and told me of the oval things on its back. I had to break the news that this poor caterpillar was dying and there was nothing I could do. I’ve attached the most recent photo of our poor caterpillar in case you want to use it on the site.

Tobacco Hornworm parasitized by Braconid Wasp

Thanks for the update Jessica,
Daniel has still not told Milo, but he did notify her father that he would pay a visit and provide an explanation.  Your Tobacco Hornworm was a goner before you discovered it.  It had been parasitized by a Braconid Wasp.  The Braconid lays eggs by “injecting” them into the Hornworm with an ovipositor.  The larval Braconids feed upon the internal organs of the Hornworm, eventually emerging to pupate on the surface, which your photograph illustrates.  Braconids are considered biological control methods for many agricultural pests, though their hosts are not limited to plant feeding insects.  Most Braconids are very species specific when it comes to the choice of where to lay eggs.

Update on Mt Washington Tobacco Hornworms
August 24, 2010
Daniel told Milo and she was understanding.  Daniel spotted this Tobacco Hornworm on the Caspian Pink, and he is going to let Milo know there is a caterpillar for her.  He is going to recommend a terrarium with a live potted tomato plant for raising it.

Tobacco Hornworm in Mt Washington

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