What's That Bug? does not endorse extermination

Caterpillar emergence
Location: Pittsburgh, PA
May 15, 2011 9:35 am
I need to know the emergence dates of the following moth species. They have been stored in my garage since last fall. All but the Polyphemus were hand-reared. I live in Pittsburgh, PA. The moths are Promethea, Royal Walnut and Polyphemus. Thanks!
Signature: June

Hickory Horned Devil: early instar

Dear June,
We don’t believe we can predict with accuracy the exact emergence dates for the Giant Silkmoths you have listed because emergence is not something that can be calculated by counting days, weeks or months.  Temperature and other climactic conditions are significant factors.  However, we can use historical sighting information on adults of the species to try to predict emergence dates.  Since Giant Silkmoths don’t feed as adults, their average longevity would be about a week, during which time they mate and reproduce, if they are lucky, though many individuals provide food for other creatures and never manage to mate.  One of our favorite yearly activities involves tracking the northern emergence patterns of the Luna Moth which began in Texas in late February this year.  Our most northern reports thus far this year have been from Virginia and Iowa, and we expect to begin hearing from Main and possibly Canada by late May or early June.  Later in the year, reports of a second brood will come again from the southernmost portions of the range in Texas and Florida
We don’t really track the other Giant Silkmoths the way we do the Luna Moth.  Starting with the Promethea Moth, according to BugGuide:  “One brooad flies June to July northward. Two broods southward, flying March to May and July to August.”  The data page on BugGuide with information on sighting in specific states has sightings in March, June and July in Ohio and May and July in Pennsylvania.  The March sighting might have been a cocoon since various stages of the metamorphosis are not aggregated in the data presentation.  We would predict a June hatching for your moths.  Regarding the Royal Walnut Moth or Regal Moth, the adult of the Hickory Horned Devil you have provided as an illustration, BugGuide indicates:  “Adults fly from late May to September” however, that is information spread out over the entire range.    The data page on the Regal Moth on BugGuide indicates sightings from June through September in Pennsylvania and July and August for Ohio, but that information would include adults and caterpillars, and we always get Hickory Horned Devil sightings in September.  Our best guess is that you can expect emergence of the Royal Walnut Moth from the pupa in June, or possibly as late as July.  Regarding the Polyphemus Moth, BugGuide indicates:  “In southern United States, adults fly April-May and July-August (2 broods); in northern part of range, adults fly from May to July (1 brood).”  According to the data page, sightings in Ohio run March to September exempting May and those for Pennsylvania are from May to August.  Based on that information, we might expect your Polyphemus Moths to hatch the soonest, possibly beginning now and into June.

Thanks, Daniel!  I have been successful in the past with the Promethea as far as mating and collecting eggs.  I would like to try the same with the other moth species.  I’m thinking it might be best for me to attach the cocoons to the inside of the metal hardware cloth cage that I have used for the Promethea and wait to see when each emerges.
Thanks for your efforts in researching my questions.  I appreciate it very much.

What's That Bug? does not endorse extermination
Location: Pennsylvania

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