Fall West Coast Ladies Are Here

Today we found a bunch of West Coast Lady (Vanessa annabella) eggs now as they are starting to come into season.

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Near the end of July, we made a post about all of the new species starting to trickle in as the season becomes ripe for them. One of them was our most common lady, the West Coast Lady (Vanessa annabella). We have frequently observed this species as being most abundant during the winter, but start coming in just about now, when fall is near. 

Today, we found for this first time this summer, a few scattered wild mallow (Malva) plants growing on the grass that were covered in West Coast Lady eggs. Like the Anise Swallowtail's (Papilio zelicaon) beloved sweet fennel (Foeniculum vulgare), this mallow is an introduced weed that colonizes with ease. Almost every unattended grassy area has some. But despite looking for eggs for months, we have not been able to find any until today.

We counted a total of fourteen eggs, all collected from three tiny (probably regenerating) mallow plants outside a dog park. We also found a hatched egg with a newborn right next to it as well as a single third instar. ​

When we took these home, we were curious to compare them to the very closely related Red Admiral (Vanessa atalanta) that we are currently rearing a number of right now. The two species are even known to possibly hybridize in areas that they overlap, such as where we live. The West Coast Lady is the smallest of all our Vanessas. and when we compared an egg to a Red Admiral egg that we found today the size difference was quite evident. The Red Admiral eggs seem to be more translucent and a richer green, with the little ribs more clearly defined since they are larger; the West Coast Lady eggs are sort of just a murky milky green. The size difference in the caterpillars was significant too. The third instar we found was much smaller than the third instar Red Admiral in every aspect. 

A main distinction between the West Coast Lady and Red Admiral caterpillars besides size is that the former always (or, at least, all of those that we have seen) bear yellow stripes running along the side. These stripes are present in Painted Lady (Vanessa cardui) as well, but not found in the Red Admirals. On top of that, the West Coast Lady caterpillars tend to vary less in color and are most often completely black except for the stripes; the Red Admiral black forms usually have colored spiracles and feet. 

- Brian