Collecting Promethea Silkmoth Cocoons on Spicebush

After locating spicebush (Lindera benzoin) at the Mundy Wildflower Garden (Ithaca, New York) for the purposes of finding Papilio troilus larvae, we inadvertently stumbled across promethea silkmoth (Callosamia promethea) cocoons on them!

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We had originally gone out today intending on collecting some spicebush swallowtail (Papilio troilus) larvae at the Mundy Wildflower Garden, which is one of the few places around with lots of spicebush plants (Lindera benzoin). It took us a little while to find our very first troilus larvae, but the excitement didn't stop there, as we stumbled across six promethea silkmoth (Callosamia promethea) cocoons hanging from the spicebushes!

Despite that we have reared most of the North American Saturniids in captivity, we have never seen a wild cocoon in our lives. Back on the west there were only two species, Antheraea polyphemus and Hyalophora euryalus, but they appeared to be absent or extremely rare in our specific area, especially the latter one. Here on the east, we now have a strong representation of this family - there should probably be at least six or seven species. It's a complete shock to us that you can find cocoons simply hanging from a plant here so easily. the leaves haven't even fallen from the deciduous trees yet and the cocoons were still quite conspicuous due to the curling of the leaves and brown silk. 

All six cocoons were directly on the spicebush plants, which was clearly the larval host, but one of them was empty and looked very old and faded (perhaps last year's assuming they are univoltine here in the north?). The leaves of some of the cocoons had already wilted and died, but the cocoons were still firmly fixed to the branch due to the shiny brown peduncle at the top of the cocoons, which are meant to hold to cocoons on throughout the winter. Though there were dozens of spicebushes along the trail, the cocoons were all located quite close to each other, suggesting they are siblings. It's interesting to note the choice of host here as promethea is a polyphagous species, feeding on mostly fragrant deciduous trees. Like most polyphagous Saturniids though, it is likely a regional specialist meaning it specializes on only a few hosts per region, and spicebush is probably a preferred hosts here.

After taking the cocoons home, we cut off most of the excess leaves and branches stuck to the cocoons, but left some on just to keep the natural look. We did a rough weighing (not accurate, though, since there was still plant material stuck to them), and they seemed all fairly large and healthy in size. Parasitized or diseased cocoon should usually be small and light, though ther's no gauruntee these aren't.. 

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Authors
Alan Liang

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