Spicebush silkmoths

mating promethea moths 1

It never fails to amaze me how little we know about our neighbors here. I’ve been noticing these curled-leaf cocoons on spicebushes for years, but never realized that they were most likely the work of the promethea moth, A.K.A. spicebush silkmoth. In fact, I’m embarrassed to admit that we initially mis-identified this mating pair on a spicebush next to the barn as cecropia moths — one of the three or four other species of giant silkmoths that occur on the mountain.

mating promethea moths 3

The female eclosed sometime this morning. Our neighbors Troy and Paula, who are painting the barn for us, spotted her clinging to her newly vacated cocoon around noon. Late in the afternoon, Troy called to say that a smaller, darker moth had joined her — literally. So presumably she had been busy releasing pheromones, broadcasting her presence to any male in the vicinity. As the Wikipedia article about moths of their family, the Saturniidae, puts it,

Adult females emerge with a complete set of mature ova and “call” males by emitting pheromones (specific “calling” times vary by species). Males can detect these chemical signals up to a mile away with help from sensitive receptors located on the tips of their featherlike antennae. The males will fly several miles in one night to locate a female and mate with her; females generally will not fly until after they have mated.

Since the mouthparts of adult saturniids are vestigial and digestive tracts are absent, adults subsist on stored lipids acquired during the larval stage. As such, adult behavior is devoted almost entirely to reproduction, but the end result (due to lack of feeding) is a lifespan of a week or less once emerged from the pupa.

mating promethea moths 5

I’m not sure why they’re named after Prometheus, but whoever named many of the most spectacular North American silkmoths (luna, cecropia, polyphemus, io) seems to have had a thing for Greek mythology. Perhaps the female’s coloration suggested fire?

mating promethea moths 6

Spicebush isn’t the only host plant for promethea moth larvae, but we have many of the others, too, including sassafras, tuliptree and white ash. This does show the value of landscaping with natives, I think — I’ve planted spicebushes all around the place. This one was a volunteer, but I made sure it wasn’t crushed when they took down the old corncrib last year. It currently hosts six other silkmoth cocoons, possibly all prometheas. Here’s how it looked the autumn before last, when it was covered with berries:

corncrib spicebush

Those berries are not only highly sought-after by birds, but they taste just like allspice, and can be dried, crushed and used as such. I’ve used both the berries and the leaves to flavor beer. In fact, I included spicebush leaves in the herbal mix for the batch of homebrew I’m drinking now — I had to prune the bush next to my front walk and didn’t want to waste the prunings. They joined juniper berries, yarrow tops and ginger root, plus a blend of wheat and barley malts, for a refreshing summer ale.

newly emerged spicebush swallowtail 1

Spicebush is also the namesake of, and one of the main hosts for, the spectacular spicebush swallowtail butterfly. So I’d better be careful and not pick too many leaves for my own use. A lot of hungry caterpillars and silkworms will be needing them soon.

6 Replies to “Spicebush silkmoths”

    1. Glad for the coincidence with your reading! I imagine the NC mountans are great for a whole host of Saturniids, including the hickory horned devil and the tuliptree silkmoth.

  1. Dave, I wonder if you’re notified of comments on older posts….? (I’m catching up with reading )Just yesterday I vowed to get some spicebush seed this year because it’s so easy to grow and any surplus seedlings make money for my conservancy. Last year I didn’t collect any seed at all because I forgot until it was too late. Could you look at the date of that photo of the shrub all seed-laden? It would help me in planning. thanks

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