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Entomology (Study of Bugs)/Swallowtail Caterpillar Dying


Dying Caterpillar
Dying Caterpillar  

Can you please help me to figure out what may have happened with this little caterpillar? I have raised dozens of swallowtails and I have had this one since the beginning as he came in on some parsley I harvested. Since he was so tiny I didn't put him back outside because there were about 6 others who were full-sized in the parsley patch. So I kept him on the parsley inside, grown by me and untreated - same parsley everyone else is eating outside. He did all his molting and was nearly ready to form a chrysalis. Last night before bed I checked on him and he was fine and he was eagerly munching away on the parsley but when I got up this morning his whole back end was shriveled, gray and looked wet. I have included a picture. I would really like to know "what" happened so that if possible, I may prevent this from happening again.

Thanks in advance for any input.

Hi Kathleen
The survival rate of insects is low. They are subject to attack from bacteria and internal parasites. I suspect that one of these is the cause here. I believe that a puncture of the skin before the last stage begins can also be at fault. I am sorry but I do not believe that you can prevent these events

Entomology (Study of Bugs)

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Walter Hintz


I can answer any questions about insects and spiders.


I have taught science for over 57 years. I am presently teaching biology at the college level. I have done extensive graduate work in entomology.

Momentum Magazine The Ohio Journal of Science

B.S. In Ed Kent State Unuv M.Sc The Ohio State Univ National Science Foundation Fellowships: Electron Microscopy Univ of California Entomology Kent State Univ

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