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Braconid Wasps Pupating and Emerging

8-29-14 braconid wasps 010Tobacco Hornworms, Manduca sexta (often found feeding on tomato plants and confused with Tomato Hornworms, Manduca quinquemaculata) are often the target of a species of a Braconid wasp (Cotesia congregata) 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 spin silk pupa cases (cocoons) on the skin of the dying hornworm caterpillar, inside of which they transform into winged adults within four to eight days. 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. (Thanks to Emily and Joe Silver for photo op.)

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5 responses

  1. Susan Holland

    Wow! Amazing photograph, and really fascinating information! Thanks for teaching me something I would never have known about …. Again!

    August 29, 2014 at 12:36 pm

  2. Joanne Cote

    fantastic info. yes I thought it was the tomato hornworm. how can one tell them apart?

    August 29, 2014 at 1:08 pm

    • The tobacco hornworm larva (Manduca sexta) is generally green with seven diagonal white lines on the sides and a curved red horn. The tomato hornworm (Manduca quinquemaculata) has eight V-shaped marks on each side and its horn is straighter and blue-black in color. These “hornworms” are the larvae of hawk or sphinx moths, of which the hummingbird moth is a member.

      August 29, 2014 at 3:36 pm

  3. Wonderful photos. I know from experience how hard it can be to get the timing right for the pictures we see posted in your blog.

    August 29, 2014 at 7:54 pm

    • Thank you so much, Tom. It’s interesting to see that there’s no correlation whatsoever between how much time/effort a post takes and the number of comments it gets!

      August 29, 2014 at 9:28 pm

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