Our Third Vanessa: Red Admiral

Today when we were down at Tilden Regional Park (Berkeley, CA), we found a handful of Red Admiral caterpillars (Vanessa atalanta) as well as a chrysalis, making our third Vanessa.

---

 Alameda County and much of the East Bay is home to only four species of Vanessa: the Painted Lady (Vanessa cardui), the West Coast Lady (Vanessa annabella), the American Lady (Vanessa virginiensis), and the Red Admiral (Vanessa atalanta). The Vanessas are classic brush-footed butterflies (Nymphalidae) in that they are migratory, or exhibit a systematic dispersal of adults throughout the year. The world famous Painted Lady (literally the most widely distributed, cosmopolitan butterfly on the planet) fluctuate greatly from year to year in our region, only showing up in swarms in outbreak years; most years we rarely see in urban Albany, especially during the summer. The West Coast Lady it perhaps the most common of the four in Albany and often breed in the winter in urban areas (they too are less common during the warmer months). American Ladies, on the other hand are quite rare and are rarely at all, if ever, seen in the Albany portion of Alameda. Lastly, the Red Admiral, though also fairly common and more abundant in the cooler months, is more commonly seen in very urban areas (i.e San Francisco) and is hard to find in the larval stage since its host plants (Urticaceae) seem to be quite rare here.

Based on these profiles, it is easy to understand what we have and have not reared over the years. In the past, we have consistently collected huge numbers of West Coast Ladies during the winter and have had great success rearing them. The Painted Lady have managed to sneak in very occasionally with our West Coast Ladies while searching on the latter's favored mallow host plants (Malvaceae) and on 7/9 we found two caterpillars on milk thistle (Silybum marianum) at Tilden Regional Park in Berkeley, CA. Of course, we have never found an American Lady to this day. But the Red Admiral should have still been possible. . . 

Today when we went to Tilden to pick pipevine leaves (Aristolochia californica) for our Pipevine Swallowtail caterpillars (Battus philenor), we decided to investigate the area around the riparian corridor on which the pipevine was growing. The most common nettle utilized by the Red Admiral is stinging nettle (Urtica dioica) is a common component of the riparian environment due to its need for moist soil. Sure enough, we found stinging nettle growing along the banks of the (mostly dried) creek as well as the nearby butterfly garden. Although it was in the evening (8 PM) and the sun was setting, we still had a chance to investigate the nettles (We were not prepared to do this though and had only a plastic bag to use as a glove to protect us from being stung!). 

Very quickly, we noticed that the plant was or had been inhabited by Vanessa caterpillars. They were covered in their little rolled up leaf nests filled with frass. Despite the fact that there were so many, most were quite obviously empty because the caterpillars make new nests with each molt, or when they have finished eating the leaf. But some of the larger, less eaten nests were more hopeful. Upon opening one of these, we were pleasantly surprised to find a Red Admiral chrysalis embedded neatly within the silken nest; the caterpillar had decided to pupate right there on the plant! It was quite clearly that of a Red Admiral and not a Painted Lady, the only other Vanessa that would potentially feed on nettle due to the blunt head and stout body (Painted Lady chrysalises are a bit pointy at the head and elongated). Looking around for more, we gathered a total of six caterpillars, five of which were fifth instar. Because it was getting dark, it was difficult to search for eggs, though we are sure that they are there because when we got home we discovered one on a leaf that we picked! 

It is lucky that we also have a Painted Lady chrysalis currently as well so that we can use it to compare the chrysalises and butterflies of the two related species. However, it would have been even better if we had a West Coast Lady instead because, between the West Coast Lady and the Painted Lady, the West Coast Lady resembles the Red Admiral much more and is more closely related (there have been reports of them hybridizing in regions where their populations overlap such as in California!). However, like all Vanessas, the caterpillar and butterfly appearance can vary hugely within the species itself (there are many recognized aberrations, too) so any comparison would be meager without a larger sample size. Nonetheless, the pictures of the chrysalises are shown below; the right in each image is the Painted Lady and the left is the Red Admiral. The third image shows an emerged West Coast Lady chrysalis to the far right.

- Brian