Found Two Papilio polyxenes asterius Eggs and a Female at Cornell Botanic Garden

We found two fresh black swallowtail (Papilio polyxenes asterius) eggs, one on caraway (Carum carvi) and one on dill (Anethum graveolens) sprouts growing next to the caraway, and a female ovipositing on bronze fennel (Foeniculum vulgare "purpureum") at Cornell Botanic Garden. This post discusses polyxenes in our region. 

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We found two fresh eggs, shown below, at Cornell Botanic Garden, one on caraway (Carum carvi) and one on dill (Anethum graveolens) sprouts growing next to the caraway. Around 5 p.m. we saw a pristine female fly into the garden that attempted to oviposit on the bronze fennel (Foeniculum vulgare “purpureum”) growing close by. As it stopped to oviposit, we captured it with a net. There is a distinct possibility that this was the same female that laid the two eggs that we found. These sightings come as a great surprise to us, especially considering the season is early and we have yet to see much evidence of any swallowtails in flight yet, because we have previously struggled to find this species at the Botanic Garden or anywhere around the Cornell Campus area of Ithaca. Until now we had never found any eggs of this species since coming to Ithaca, nor had we seen any adult butterflies despite the presence of a number of what should be palatable Apiaceae in the areas we visit. The only evidence we had of the species’ existence, locally, is when we found a fifth instar larvae on wild parsnip (Pastinaca sativa) in early July of last year at the North Campus entrance to Beebe Lake. There is a possibility that polyxenes begins flying earlier than the other swallowtails and that the early season is the best time to find them, which would explain why we had little luck in previous years where we never looked during this time of year.

There are a lot of golden alexanders (Zizia aurea), an early season umbel, growing and blooming currently along and around Beebe Lake, and in Mundy Wildflower Garden, but we haven’t checked these closely. Some of the wild parsnip has also already grown out, too, but no Queen Anne’s lace (Daucus carota), which is mainly a late seasoner. Besides caraway and dill, there are also a few stands of fennel, both Foeniculum vulgare and its purple variant “purpureum”, a few exotic Apiaceae species that we aren’t familiar with, and rue (Ruta graveolens) at the Botanic Garden. We’ll need to take a good look at some of these now, now that we know polyxenes is here and in flight. Of these, the common cultivated species (fennel, dill, and caraway) seem most hopeful as they are nutritionally superior and less toxic compared to the wild type umbels and likely preferred if encountered by the females and because there are fewer, larger plants that are easy for us to look at. The three wild species (golden alexanders, Queen Anne’s lace, and wild parsnip, an invasive) seem like fairly legitimate choices though, too.

The female we caught, shown below, is on the larger side by our Bay Area P. zelicaon standards, although we lack context with the local polyxenes themselves since this is the first wild adult we have encountered here. 

Its abdomen is remarkably plump and the wings show no sign of damage. We suspect it could not have eclosed more than a few days ago, especially since the season is early. When we tried to feed it sugar water solution, it refused, perhaps because it was flustered and/or not hungry. For oviposition, we set it up in a small black popup cage in a climate chamber near white light with cuttings of bronze fennel in a flask. This is the same setup we used to get P. zelicaon to oviposit earlier this month.

​​It is interesting to examine the phenotype of this specimen with regard to it as a representative of our type locality. Something noteworthy is that this individual has a significant amount of yellow scales invading from the exterior of the fore- and hindwings. The females of other populations may not have nearly as much since yellow coloration is undesirable for mimetic accuracy of Battus philenor, and B. philenor is not present in Ithaca. What is also interesting is that its body is shorter, fatter, and noticeably hairier than those of our California Bay Area derived zelicaon, a characteristic that seems to be common among the eastern species. The body and wing shape of local P. glaucus are also shorter, fatter, hairier, and overall more concave than Bay Area P. rutulus, which are more convex (triangular) with long, tubular abdomens, for example. This trend may have to do with differences in climate factors, such as humidity.

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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.

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