Every Month Has a Different Set of Butterflies: July

Today, as we were out for a walk to down to the Ohlone Greenway at Lincoln Ave. (El Cerrito, CA) to collect Gulf Fritillaries (Augraulis vanillae), we observed a different set of butterfly faces than the time we went down last month in June.

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Most butterflies and moths (and most all insects, at that!) follow some kind of breeding pattern throughout the year. If you have ever observed a species in your area, you will quickly notice that there are months when the species does not breed or fly and other times when they are "in season" and are at their peek abundancy. In general, seasonality of a specific Lepidopterans is strongly correlated with the seasonality of their resources (food) as well as climate. That's why so many of them diapause through the winter and emerge in spring when it begins to warm up and the new growth is just setting in. 

A big exception to this can be found in many brush-footed butterflies (family Nymphalidae), many of which more or less follow some sort of migratory schedule or dispersal of the adults to different regions (they don't diapause). Today as we were going down to the Ohlone Greenway at Lincoln Ave. to find some male Gulf Fritillaries (Augraulis vanillae) for hand-pairing purposes, we noticed some common brush-foots that we hadn't really seen in the same numbers in June. June is usually a fairly big month for the traditional spring flight butterflies (those that diapause in the winter and have their largest flight in the spring) like our swallowtails -- the Anise Swallowtail (Papilio zelicaon), Pipevine Swallowtails (Battus philenor), and Western Tiger Swallowtails (Papilio rutulus) -- which we saw a lot of back then but not as much now. What we didn't see a whole lot of were Gulf Fritillaries (relatively) and Monarchs (this year is an enormous year for Monarchs, the biggest in over decade, but we noticed a decline when summer started; following their migratory schedule, this is usually the one month that they are not here).

Now that it's July, we are seeing an influx in both species. Yesterday, we noticed two Gulf Fritillaries flying around our yard in the morning, something we had not witnessed this entire year. This morning we saw two more, which is actually why we decided to go down to the Ohlone Greenway in the first place this afternoon (there is a big passionflower vine there where they breed). Over there we saw at least five more and even managed to catch three of them (though we still are not successful with hand-pairing them). As for Monarchs, we saw maybe five or six of them on throughout the trip and even had the chance to witness a pair of them mating on the grass. In over a decade of watching for Monarchs, we have never seen them mating in the wild. At this point we're beginning to wonder if they have actually taken up residency for good this year since they are breeding during the summer and not just colonizing the area as temporary migrants.

But now let's back-track. When we were just half a block away from our house, just as we were talking about how there were no West Coast Ladies (Vanessa annabella) this entire summer (or their caterpillars and eggs on the mallow host plants [Malvaceae]) so far and were worrying about not finding them at all this year, we saw one land someone's lawn. We had actually brought a butterfly net with us that we were going to catch the Gulf Fritillaries with, so we tried to catch the West Coast Lady but it was just too fast! Soon after, we also saw a Painted Lady (Vanessa cardui) flying with the West Coast Lady on the same lawn. We hadn't seen either species in the city in months and we spend hours outside everyday.

- Brian