An online resource based on the award-winning nature guide – maryholland505@gmail.com

Tobacco Hornworms & Brachonid Wasps

Tobacco Hornworms, Manduca sexta (often found feeding on tomato plants and confused with Tomato Hornworms, Manduca quinquemaculata) are often the target of a species of Brachonid wasp that parasitizes beetle, moth, fly and sawfly larvae. The adult wasp lays her eggs inside the hornworm with her long ovipositor. The eggs hatch and the wasp larvae feed on the caterpillar. Eventually the wasp larvae emerge and form white pupa cases on the skin of the dying hornworm larva, inside of which they transform into winged adults. Braconid wasps are extremely good at locating hornworms, even when there are very few to find. Because they parasitize hornworm, cabbage worm, aphid and gypsy moth larvae, Braconid wasps are considered important biological control agents. If you want to discourage Tobacco Hornworms in your tomato patch, allow the wasps to complete their metamorphosis – this accomplishes both the demise of the hornworm, as well as an increased population of Braconid wasps.

5 responses

  1. Libby

    Hi Mary, Do you have a photo of the Brachonid wasp to post?

    August 11, 2012 at 9:58 pm

  2. That is extremely gross and extremely cool! And I’m always delighted to learn about a new helpful garden insect. Thanks!

    August 11, 2012 at 10:19 pm

  3. Richard

    I have a huge number of large white (butterfly) caterpillars that have ascended to there place of transformation , and 90% have these yellow furry egg like things eminating from them , is this the wasp larvae ?

    June 27, 2016 at 6:06 am

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