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Callosamia Promethea


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I thought i needed to introduce anyone on this forum who's into giant silk moths, or lepidopterans in general, to my favorite species. There won't be any pictures, but a quick google search will demonstrate what I'm talking about. They definitely aren't the biggest or most spectacular native silk moth, and arguably not the most beautiful, but they have an interesting life history, very attractive caterpillars, and are easier to raise than cecropias and other larger species. When the caterpillars are younger, through the first two molts, they are striped with black, white and yellow and feed in clusters. Some people say they mimic monarch caterpillars, but i doubt that. i think they resemble poisonous Grapeleaf Skeletonizers. After their third molt, they become a powdery whitish- blue color and develop bright yellow knobs (sort of like cecropias) on their thorax and anterior. The knobs have little bristles on them. I can't imagine what object in nature they are meant to look like at this stage, although their color does sort of match the undersides of sassafras leaves. (sassafras is a host plant.) After molting a fourth time, they either stay the same or the knobs turn varying shades of orange. and at the fifth and final molt, they become more green and less whitish blue and the knobs turn bright red and smooth, with no bristles. i guess the knobs look kind of like cherry spindle galls. (black cherry is their favorite host plant.) The cocoon is small and thin, and stays on the tree all winter because the caterpillar spins silk on the petiole of the leaf it wraps around its cocoon. When the adults emerge, they are fairly small as far as silk moths go- usually not larger than 3 inches across. My favorite part about them is how dimorphic they are: the females are sort of a reddish brown color, like a terracotta flowerpot, and have patterns similar to the cecropia moth. The males, on the other hand, are a dark velvety black with cream colored wing margins. But the best part is that when you mate them, the males that smell the female arrive in the middle of the afternoon! You get to see wild moths in flight, sometimes dozens, at around 4:00 pm, a much more convenient hour than for cecropias. (about 4 am.) The males apparently mimic poisonous pipeline swallowtails. Anyway, i believe that every moth enthusiast must try this species sooner or later!

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Well, there's this paper I read once about declines in various moth species... There's this evil generalist parisitoid called Compsilura Concinnata, a tachinid fly introduced from Europe to kill gypsies and corn ear worms, that loves to feast on the juicy insides of silkmoth cats. When thousands of caterpillars were placed on trees for a week, 80 percent were parisitized. So in most areas with this fly, certain large moths vanish. And they can't wait for the fly to die out due to a lack of hosts and repopulate, because the fly also survives on other larvae including sawflies and other non- caterpillars. Polyphemus and lunas are still fairly common, but cecropias and prometheas are gone from many areas. Hickory devils and imperials are completely extinct from much of their former range. Although light pollution is a big problem, it's probably not for this particular species because the males ( which for most moths are the ones that travel in search of females and thus get sidetracked by lights) are diurnal, and thus do not appear at lights. Female prometheas do turn up at lights occasionally, but in general female moths are spending more time crawling through the shrubbery laying eggs than flying out in the open. And even without the fly, silkmoths are uncommon to begin with- i see 2- 3 wild moths besides the ones attracted to caged females a year max. And another thing about prometheas is that it's hard to predict when their will be a "hatch"- Lunas have their hatch on a warm night in may, cecropias in early June, polys in late June etc... But the promethea hatch can happen anytime from may to late July in the same place on different years. They might all hatch at once, or some cocoons will not hatch when the others do and wait till later. The only way to predict when prometheas will hatch is by having your own cocoons and seeing when they hatch. So it's an elusive and unpredictable species that may or may not be extinct in your area. Of course, even if you go years and never spot a trace of them, silkmoth's amazing sense of smell allows them to exist in extremely low population densities.

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