caterpillar with white sacs
Location:  Church Hill, Tn
August 11, 2010 6:17 am
Can you identify this caterpillar found
in my backyard?
Linda Luster

Parasitized Hornworm Larva

Hi Linda,
Your caterpillar is a Sphinx Moth Caterpillar, commonly called a Hornworm.  Since the caterpillar was found on tomato (as evidenced by the name on the photographic digital file), it is one of two species in the genus
Manduca.  It might be the Carolina Sphinx, Manduca sexta, whose caterpillar is known as the Tobacco Hornworm (see BugGuide), or it might be the Five Spotted Hawkmoth, Manduca quinquemaculata, whose caterpillar is known as the Tomato Hornworm (see BugGuide).  The distinguishing features on the caterpillar are obscured by the angle of view and by the pupae of a Braconid Wasp. There are many different Parasitoid Wasps that look very similar, and it is believed that Cotesia congregata may be host specific to Manduca sexta, according to BugGuide.  The female wasp lays her eggs inside the caterpillar using her ovipositor.  The eggs hatch and the wasp larvae feed on the inner organs of the caterpillar, eventually burrowing to the surface where they form the cocoons visible on your specimen.  The caterpillar is doomed from the point the eggs are laid, but it continues to live and feed so that it can provide nourishment for the growing Braconid Larvae.  Both the Tomato Hornworm and the Tobacco Hornworm feed on tomato plant leaves.

Thank you for your prompt response to my question. I am amazed at the wealth of knowledge that
can be found on your website. Keep up the good work.
Linda Luster
PS I grew up loving bugs and at age 55, I am still facinated by them. I am one of 8 children. My sister, who
is 2 years older than me, hated bugs as we grew up. Since there were always baby food jars at our house,
I would take an empty one and go outside to “catch bugs”. One night, I took the jar with me to bed. I shared
the same bedroom with my sister. During the night, the lid accidentally came off and the bugs were in our bed.
My sister woke up, screaming. The bugs were rolly-polly’s and were crawling in the bed. Needless to say, my mom
ask me not to take them to bed with me anymore.
Thought you might need a chuckle.


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One Response to Hornworm parasitized by Braconid Wasp Pupae

  1. Jessie0904 says:

    My daughters found a horn worm with the eggs on it. So we looked it up and found out that the wasp larvae will eventually kill the worm. My daughter was so heart broken she took an old toothbrush and brushed all the eggs off. She wants to know if the worm will survive now?

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