Rearing notes for the larvae from our hybrid crosses between female black swallowtails (Papilio polyxenes asterius) (orig. Ithaca, New York) and male anise swallowtails (Papilio zelicaon) (orig. Albany, California). ​

Rearing notes for the larvae from our hybrid crosses between female anise swallowtails (Papilio zelicaon) (orig. Albany, California) and male black swallowtails (Papilio polyxenes asterius) (orig. Ithaca, New York). ​

Rearing notes for our hybrid cross between female black swallowtails (Papilio polyxenes asterius) (orig. Ithaca, New York) and male anise swallowtails (Papilio zelicaon) (orig. Albany, California). 

​Alan Liang​
​Alan 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 and photographs.

​We have returned to Albany, California from Ithaca, New York as per Cornell University's winter closing, giving us a chance to see the  preseved hybrid ♀ Papilio polyxenes × ♂ zelicaon that eclosed while we were in Ithaca.

In a post from last August (Albany Updates (8/23/17): ♀ Papilio polyxenes × ♂ zelicaon Adult Male), we mentioned how one of our hybrid pupae had eclosed back in Albany, California while our family was in Ithaca, New York. By the time our mother got home (of course, we stayed in Ithaca), the butterfly was evidently already beat itself up quite a bit based on photographs of the live specimen that our mother sent. But since we obviously did not want to opportunity to see this unique specimen go waste, we had our mother do the best she could to preserve it via pinning. She is nowhere near an experienced pinner, but her work is good enough so that we can more or less see everything on the butterfly. 

Below are the photographs of the front and back of this male hybrid. 

For some perspective, we also took shots of the hybrid next to pinned male P. polyxenes asterius and female P. zelicaon (wing pattern sexual dimorphism not too significant in zelicaon​, so should be an okay comparison). ​

At first glance, the hybrid may resemble the polyxenes more, simply because of the blackness. However, it should not take long to realize how it appears to be more or less a perfect intermediate of the two species.  

Back in Albany, our luna moths (Actias luna) have begun to eclose, anise swallowtail (Papilio zelicaon) rearing continues, and checkerspot skipper (Pyrgus communis) larva has become a prepupa. 

Today, we got some exciting yet unsettling news that two lunas (Actias luna), a male and a female, have emerged back at home. When we reared these, we had put a great deal of effort into controlling the amount of daylight they received, making sure to keep them in a dark tub for at least 12 hours a day in order to increase the chances that  would diapause. (Of course, the set up wasn't perfect as we were not always consistent about it and there are still many factors that might make it different that what they naturally experience that would cue diapause. For example, a diminishing photoperiod may have helped.) Even at the time, though, we had a bad feeling that not many of them cooperated, seeing as only a handful of the cocoons were the course and dark brown as they should be if they are diapausing. Because this is such an inconvenient time for them to be breeding and we would feel pretty terrible about making our mother deal with them, we decided the best thing to do for now is to get one pairing just to keep the line going and then pin the rest. 

As for our Papilio zelicaon, the last few are still eclosing and our mother is trying her best to hand-pair them.  She reportedly already paired a male polyxenes with a female zelicaon, but it has not begun to lay yet. The several hundred pure zelicaon eggs that we already had in the cage from the mass pairings we did before we left are making progress, but according to our mother, there are only about 80 or so caterpillars. Mysterious losses always seem to be high when rearing outdoors, even with a screen cage to protect them. . . She also found eight random caterpillars on a different fennel in our yard that we must have overlooked when we were there. 

We have reports that a hybrid ♀ Papilio ​polyxenes asterius × ♂ zelicaon male has mysteriously appeared in our tank. 

Before we left, we had thought that all of our hybrid pupae had already eclosed, except for the females that appeared to be in diapause. There should have also been exactly one pure Papilio polyxenes asterius male that had not yet eclosed (the one that we kept outside for photos and was exposed to cooler on average temperatures). Therefore, it struck us as quite odd when our mother mentioned that there were two "black" swallowtails that had emerged from our pupae tub when she checked. We told her to send us a picture and, as we suspected, one of the two very clearly appears to be a hybrid male. A while back, we had mysteriously lost a male hybrid pupa that we thought happened when we accidentally dropped a petri dish containing a few but now it is more likely that we got it mixed with the P. zelicaon pupae. 

Anyway, it is absolutely amazing that we finally have a hybrid specimen that is in good enough shape to really be looked at. (It is the individual in the far left of the photograph.) Based on our previous observations of the pharate pupae and the crippled males, we had already gotten the sense that the black from the polyxenes is quite dominant over the yellow but that many of the other traits were zelicaon-like. This new hyrbid basically confirms many things that we wrote before, although it can be hard to assess certain traits that are found on parts we can't see in the photo such as the hindwings and the abdomen. Because this is such a valuable specimen, we have asked our mother to pin it up so that we can get a closer look at it in real life should should we come back home during a break so perhaps we will make another post on it in the future. 

Well, it's been a few days since we have arrived in Ithaca and there are numerous rearing projects still in progress back home in Albany that we no longer have direct control of anymore. Fortunately, our mother has agreed to help take care of anything that are require immediate attention, at least for now. With that said, from now on we will periodically post updates on any significant events that take place in Albany as they occur and are reported to us. 

The first update is for Papilio rutulus. On the day that we left (August 16), there were still three stragglers left, including two that were unusually small and probably unhealthy. We had left the three together in a tub in darkness with heaps of willow (Salix) cuttings to ensure that they would not starve for the five days that nobody would be at home. At the time, we actually suspected that they would stop feeding before the five days, and we were correct; two of the three have already pupated into 1.08 and 1.45 g pupae and the last one is a prepupa. The 1.45 g one is quite surprising, placing fifth of 26 in weight, and was most definitely the one of the three that was not sickly. . . On the other hand, the 1.08 is third to last. The one thing to note, however, is that these weights were not necessarily taken right after pupation (well, within 24 hours), which was the procedure we used to collect all of the other data points.

The second update is for the regals (Citheronia regalis). Before we left, we were hoping desperately for the things to pupate so that we could just see it once before the rare opportunity would be lost. Unfortunately, that never happened, even after five days of being in the prepupal stage inside the incubator. In the end, it is not unreasonable for earthen pupates, especially such massive ones as these, to take an absurdly long time to pupate, but of course it was still a major disappointment. At some point during our leave, five of them did finally pupate though at 6.6, 6.62, 7.0, 7.13, and 7.94 g (again, these weights are probably slightly less than they would have been if they were taken immediately after pupation). While not unimpressive relative to other species that we have reared, these weights are still somewhat disappointing for how large the caterpillars were. Based on old records, they roughly shrank to just above a third of their peak larval weight, which is a pretty steep drop compared to most other things. Although we have not received any pictures of them yet, our mother assures us that they do not suffer from any deformities, which is a great relief given how difficult it often is with earthen pupators. 

Lastly, we come to the various machaon swallowtails, which all decided to come at the worst possible time. . . In the days before we left, we had very hastily created some hybrid pairs of P. polyxenes asterius and P. zelicaon and left what we hoped were fertilized females outside in the cage to lay eggs. After five days, all but one of these females is still alive and, according to our mother, there are no fresh eggs. Right now, it looks like we have failed this time. But hopefully we will be able to try again, now that we have easy access to P. polyxenes asterius here in Ithaca!

Update: The last rutulus pupated at 0.95 g. The collective average for the rearing is 1.258571429 (n = 27).