unusual Hyalophora cecropia cocoon in MN
On November 7, 2017 I collected an "empty" Hyalophora cecropia cocoon from a dogwood (Cornus sp) in east central MN. It seemed unusually large to me (end-to-end 3.5 inches, maximum lateral profile 1.25 inches). General color and texture suggested formation in 2016 or maybe 2017 (older cocoons get rather 'bald' and pale). The eclosion valve seemed gapped and there was also a small hole (~1/8 inch) in the uppermost opposite end. I was surprised on cutting it open to find no inner layer/bag; also no pupal exuviae, nor evident wasp or fly parasitoid exuviae; only larval exuviae and some (to me) unidentifiable junk.
While I haven't examined all that many Hyalophora cecropia cocoons, I have looked at both baggy and compact versions and cannot recall having seen one without an inner layer. I suppose the prepupal larva may have spun the outer layer and perished before constructing the inner bag? But this may not make sense since the larval exuviae were present, but no pupal exuviae.
Any ideas much appreciated!
Contributed by jim sogaard on 7 November, 2017 - 6:21pm Last updated 8 November, 2017 - 11:46am |