Rearing notes for eastern tiger swallowtail (Papilio glaucus). Stock originated as F0 ("wild") eggs from Iowa, May 2019.

Rearing notes for black swallowtail (Papilio polyxenes asterius). ​Stock originated as F0 ("wild") eggs from Iowa, May 2019.

Rearing notes for black swallowtail (Papilio polyxenes asterius). Stock originated as eggs from Ithaca New York, May 2019.

​Brian Liang
Brian Liang is a student at Cornell University in Ithaca, New York pursuing an undergraduate degree in entomology. He is co-owner and a main contributor of the Liang Insects blog, insects articles, and site design.

Two of the three captive Hyalophora cecropia females we set outside paired with wild males last night. These are the first pairings of this year.

On the third night since we started setting captive females outside to call in wild males, we finally got pairings with two of the three females. The two females were the larger of the three, one of which eclosed three days ago that failed to call in a male the past two nights, and the other of which that just eclosed yesterday. Both also happened to be in the wire cage with larger holes (1 square inch) that we switched to last night since we suspected the cage with smaller holes (1/2 square inch) that we used the past two nights was physically preventing males from copulating with the female. The female that failed to pair was the smallest of the three and was in the cage with smaller holes. This suggests that our suspicion was perhaps correct, though sample size is small and it could be a coincidence. Either way, though, we'd rather play it safe and use the one with larger holes from now on, even if there is a small risk smaller individuals could escape.

The wild males in the pairings were still paired with the females long after the sun rose and remained coupled until dawn. Like we observed last year with the wild males called in, they are extremely large compared to our captive males and even a bit larger than the females. Alas, growth in the wild must be much superior to captive, crowded, conditions even when reared in sleeves. In addition, the males have darker, more contrasting colors, with a darker gray ground color, crisper white and red margins, and darker red body. This differs from our captive individuals (both male and female), which tend to have a lighter grey ground color that is infused with more white and yellow scales and have lighter red bodies. We noticed the same thing last year and weren't sure if it were genetic or environmental. We are starting to suspect it is more environmental at this point, since the males from last year and this year have been consistently this darker phenotype. Perhaps the temperature and humidity that the cocoons diapaused or developed under affected the coloration? Not sure if we would ever know for sure but it's an interesting to note.

Rearing notes for western tiger swallowtail (Papilio rutulus) pupae. Stock originated from a single pairing between reared female and wild male in Albany, California, Summer 2017; currently in third generation.​​​​

Rearing notes for eastern tiger swallowtail (Papilio glaucus) pupae. Stock originated from wild eggs or larvae collected in Ithaca, New York, Summer 2018.

We received eastern tiger swallowtail (Papilio glaucus) and black swallowtail (Papilio polyxenes asterius) eggs from Iowa. The state of the eggs and potential differences between Iowa and local populations of the two species is speculated upon and discussed. 

Most of these glaucus eggs have already reached the late stages of the yellow mottling phase. A few are partially black and may hatch tomorrow while a few also are green and therefore likely infertile. In addition, we noticed that some of the partially developed eggs had collapsed; this was not the case with the P. polyxenes asterius eggs, which were received in the same package. This is interesting because we have struggled with hatching glaucus-group eggs in particular in the past, namely, with P. rutulus but rarely with those of machaon-group species. It may be that glaucus-group eggs are inherently more susceptible to damage than machaon-group eggs, perhaps owing to their differing ecology (glaucus-group eggs are laid on trees whereas machaon-group eggs are laid on forbs), though this is purely speculation. ​​​

​The polyxenes eggs, shown below, are in excellent shape, for the most part. They seem to be much more varied in age than the glaucus though. Some of the eggs have already almost completed development and will likely hatch tomorrow.

​Brian Liang
Brian Liang is a student at Cornell University in Ithaca, New York pursuing an undergraduate degree in entomology. He is co-owner and a main contributor of the Liang Insects blog, insects articles, and site design.