Eastern Giant Swallowtail Chrysalises Have Arrived

9/3/2016

Our Eastern Giant Swallowtail (Papilio cresphontes) chrysalises arrived today from an Ohio breeder.

The Eastern Giant Swallowtail (Papilio cresphontes) is our first swallowtail in the Rutaceae feeding subgenus of Papilio, Heraclides. While this is probably the most well known and widespread of these swallowtails, this group of swallowtails as a whole are probably the least well-known and are not as widely distributed in North America as the tiger (Pterourus) and black (Papilio) group swallowtails since there are fewer species in the subgenus. The closely related sister species, the Western Giant Swallowtail (Papilio rumiko), is here in California, but its introduction in the south is extremely recent; they have yet to increase their range to Albany.

Today we had 12 Eastern Giant Swallowtail (Papilio cresphontes) chrysalises arrive from a breeder in Ohio, the same one who sent us Eastern Tiger Swallowtail (Papilio glaucus) chrysalises. He also sent us another four glaucuses this time as well, one of which was pharate, but we are really just excited about the cresphontes since, as mentioned before, this is the first time we have had this species.

The first thing we did (as always) was find the mass of the chrysalises, since it is interesting to us to see the relation between pupal mass and adult wingspan. We got the following numbers in grams for these twelve cresphontes: 0.8, 0.9, 0.9, 1.0, 1.1, 1.1, 1.1, 1.1, 1.1, 1.2, 1.2, 1.3. The average is 1.067 grams, which is only slightly higher than the 1.028 gram average for 25 of our wild-sourced Anise Swallowtail (Papilio zelicaon) chrysalises and only a bit higher than the 0.95 average of 44 of our captive raised and wild-sourced Hairy Pipevine Swallowtails (Battus philenor hirsuta). We never found the exact average of the Eastern Tiger chrysalises but the minimum was 0.7 grams and the maximum was 1.2 grams and based on memory, the majority were around the 1.0 or below.

Based on these results, it is a bit odd that all four of these species have such close pupal weights even though the average adult wingspan differs so greatly between them. Cresphontes' wingspan is much larger than the zelicaon or B. p. hirsuta, averaging a whopping 14 cm (5.5 in) for males and 14.7 cm (5.8 in) for females according to one source (after all, why call it the "giant" swallowtail if it wasn't big?). In our experience, zelicaon reaches 4.5 inches from enormous 1.5 gram chrysalises at the very maximum when reared under laboratory conditions (how unfair!) and is often marked lower by field guides; our B. p. hirsuta is even smaller, with our largest individuals less than 4 inches though field guides sometimes report 5 inches. Glaucus reportedly averages slightly smaller than cresphontes, which corresponds better to pupal mass (our largest glaucus was 5 inches). Clearly, both cresphontes and glaucus have much larger wings in proportion to their pupal mass as compared to the other two species. Following this kind of crazy pupal mass to wingspan ratio, the Two-tailed swallowtail (Papilio multicaudatus) would be monstrous, considering that our largest chrysalis of this species is 2.9 grams (none of them have eclosed properly yet, so we have yet to see)!

Shape-wise, the cresphontes chrysalises are typical swallowtail shape, somewhat like members of the other two groups except there is a large bulge in the middle (must be from the elongated wing shape) and the spikes on the thorax and head are softer. They somewhat resemble B. philenor of an entirely separate swallowtail tribe, chrysalises more because of the bulge. The coloration very closely matches tree bark, being a greyish bark colored brown with varying amounts of green along the sides.

Now that we have these Eastern Giant Swallowtail chrysalises, we aren't quite sure what to do. Since it is so late in the season, it is reasonable to assume they are going to diapause until next spring which the breeder also suspects (diapause patterns, however, can be hard to predict with this species since they are of tropical origin [Central America] where it is warm year round). This is fortunate since if they eclosed now, they would probably not survive a whole brood in the fall weather, though obtaining citrus wouldn't be a problem. For now, we haven't done anything with the 12 chrysalises yet and have left them in the container they were sent in, but we will eventually set up a safe container for them to overwinter.

From left to right: Papilio cresphontes, P. glaucus, P. zelicaon, Battus philenor hirsuta

From left to right: Papilio zelicaon, P. glaucus, P. creshontes, Battus philenor hirsuta

- Alan, Brian

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