Gulf Fritillary Sightings

Though Gulf Fritillaries (Augraulis vanillae) are not native to this region, the migrant stray can be fairly common from year to year depending on season. Today we had a chance to see a few down at El Cerrito's Ohlone Greenway at Lincoln Ave.!

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Typical of migratory butterflies, the Gulf Fritillary is is incapable of diapause. The butterlies are virtually year-round and generations are constantly overlapping. However, it is still more common during certain parts of the year though it is very difficult to pinpoint exactly when. Here in the Bay Area we have observed that they are common during the winter since they are so mild here. In the past, they have also been extremely common later in the summer like in August. Today, we decided to search for them anyway. 

The caterpillar's host plant is the tropical Passionflower (Passiflora spp.), but due to the fact that the vine has become so popular due to its edible fruit many species in the genus have been cultivated. In addition, it is a favorite in nurseries and gardens since it has very showy flowers and it is not difficult to locate the plant even here in Albany, CA. This is partly why the Gulf Fritillary's range extends so far, all over the U.S. 

Even though we had already searched a few passion vines this year and were unable to find any caterpillars and eggs despite occasionally seeing the butterflies all throughout the season, we still took our chances and went down to El Cerrito's Ohlone Greenway at Lincoln Ave. where there is an enormous passion vine along the trail. This is the vine where we had first encountered Gulf Fritillaries (caterpillars and eggs) three years ago in 2013 and since then has consistently the best place to find them. 

We don't know why it is so difficult to find any eggs anywhere despite having seen so many butterflies this year but perhaps the unwilling butterflies have a broader agenda than we know of. Today, we had a chance to see several butterflies fluttering around the vine, though they were either refusing to lay eggs or were males competing with each other. At the same time the the majority of the vine was dead due to the dryness of summer, but we doubt that this would really have discouraged egg laying. We were only able to collect a single newborn caterpillar, though we lost it at some point and were unable to bring it home. However, we were also able to catch a butterfly which we do believe is female, so perhaps we could get some eggs out of it. . . 

- Brian