Caterpillar - Malacosoma disstria

Moved

… Phil Huntley-Franck, 24 June, 2009 - 5:23pm

7698 - Malacosoma disstria

I think the white spot is standard equipment for this species. (no rsvp, thanks)

… Bob Patterson, 15 June, 2009 - 1:38am

about the white spot

Don't see a white spot there usually, and the spots that M. disstria does have are irregular, usually off-white, and with the long axis down the back. Being perfectly ovoid, bright white, and having the longer axis across the back, this looks like an unnatural addition, and a parasite egg or coccoon is my guess.

… Abigail Parker, 19 June, 2009 - 4:38pm

Perhaps this will help.

I've added a 100% crop of the front end of the caterpillar, where the egg is.

I'm definitely no expert, but I still think it is an egg. In other angles I have, it also appears to look like an egg, and I fear this little fellow will not live to grow wings.

… Phil Huntley-Franck, 19 June, 2009 - 11:02pm

Tachinid egg

Did some browsing in my insect guides at home and found some photos of tent caterpillars with a single tachinid egg laid in exactly that spot. (For some reason tachinids like to lay close to the head.)

Though tent caterpillars are destructive, I don't like seeing anything being eaten from the inside out, especially since tachinids that were imported to control gypsy moths and cabbage whites have drastically reduced our native silkmoths and whites/suphurs. Since the parasitized caterpillars are doomed to a slow death anyway, I interfere with nature by killing them quickly, thus also preventing the tachinid from maturing and laying eggs on other caterpillars. (A killing jar is quick, but so is putting them under a large leaf or napkin and stomping on them. If there's a robin's nest around, I leave out the body for the birds to eat.)

… Abigail Parker, 21 June, 2009 - 12:06pm

Thanks!

I happened to grab a couple of photos of the forest tent caterpillar in the park I work at in Iowa. Upon inspection of the photos later, I found one caterpillar had two small white objects attached near its head. It only took me a short search on bug guide to find your photos and discussion about parasite eggs. Confirmed my suspicions :)

… Jessica Salesman, 3 June, 2011 - 2:35pm

egg -

I too find it a cruel fate to be eaten alive from the inside. I wonder therefore, can the egg be removed without damaging the caterpillar, or perhaps the egg could be crushed with tweezers? at least in the case of a beneficial or innocent caterpillar?

On the other hand, there is a robin's nest in my shed, about 40 feet away from this stump, that I visit in my daily bugtography rounds, and Mr. & Mrs. Robin are into their second brood this year . . . .

And now having run out of hands, that leaves open the question, should I interfere at all?

… Phil Huntley-Franck, 21 June, 2009 - 10:40pm