Yes to the Sassafras... Variability in host-plant quality for the larvae of a polyphagous insect folivore in midseason: the impact of light on three deciduous sapling species T.L. Osier* & S.M. Jennings Department of Biology, Fairfield University, Fairfield, CT 06824, USA *Correspondence: T. L. Osier, Department of Biology, Fairfield University, Fairfield, CT 06824, USA. E-mail: tosier@mail.fairfield.edu ÂPresent address: Biology Department, Bassine Building, Brandeis University, 415 South Street, Waltham, MA 02454, USA. Copyright © 2007 The Authors Journal compilation © 2007 The Netherlands Entomological Society KEYWORDS light availability  Acer rubrum  Prunus serotina  Sassafras albidum  Callosamia promethea  Lepidoptera  Saturniidae Abstract We examined the effects of light availability on the suitability of foliage from red maple (Acer rubrum L.) (Aceraceae), black cherry (Prunus serotina Ehrhart) (Rosaceae), and sassafras [Sassafras albidum (Nuttall) Nees (Lauraceae)] for the larvae of the promethea moth, Callosamia promethea Drury (Lepidoptera: Saturniidae), in midseason. We identified replicate sun- and shade-grown saplings of red maple, black cherry, and sassafras from naturally growing populations in the field. Foliage collected from the experimental saplings was bioassayed using early instars of the promethea moth and assayed for nitrogen and carbon content. Promethea moth-larval performance and survivorship was highest on sassafras, intermediate on black cherry, and lowest on red maple. Larvae feeding on foliage from plants grown in the sun performed better than from those grown in the shade; the effect of light did not depend on sapling species. Foliar nitrogen content varied among the sapling species and was higher, overall, in foliage from plants grown in the sun. Nitrogen concentration related strongly and positively with larval performance and accounted for a great deal of the variation in performance both among the sapling species and between the sun and shade treatments. During midseason, foliar nitrogen content is determined by light availability, it varies among sapling species, and it is likely the primary constituent determining host quality for folivores on these sapling species.

I tried suggesting something like that too, Larry. He's just adding 2 repetitive posts a day. A post called "Woollybear's Gallery" would be so much more useful. It would give you one place to look at all his photos and commentary. We had someone like this on another list. Really useful messages just get buried. It destroys the structure of a forum. I am trying to bump older messages up. K

Sure, they are alive, but are they able to hatch like this? Seems like the cocoon would offer protection. I really want to know! No one has addressed my concern of ripping these out of their cocoons, does that do them any harm?

Cecropias have a cocoon for a reason: It protects the pupa. They don't stand up well to a lot of handling. I've cut open a zillion cecropia cocoons but I put the pupa back when I'm done examining it. Since you have it out of the cocoon, you'll know that a cecropia is getting ready to eclose when the pupa lightens up and the abdomen extends. I tell if a cecropia pupa is alive by weight, rigidity, and wiggling. When it is dead, the pupa dries up and gets lighter and rigid. Wiggling is a sure sign it is alive but cecropias are not big wigglers especially when compared to a luna. Conditions during its life as a caterpillar determine when it will eclose. It is the only Lep I've raised that is unaffected by the conditions I've overwintered it in. If I kept the cocoons inside or outside, the moths eclose during the time window I expect.