Collecting Gulf Fritillary Larvae in Winter

We collected some Gulf fritillary (Agraulis vanillae) larvae on the passion vines (Passiflora sp.) along the Ohlone Greenway Trail (El Cerrito, California).

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It's been months since we actually went out and collected any insects because it got too cold in Ithaca to find anything. However, having returned to California for the past few weeks, the weather has actually been quite reasonable (at least compared to Ithaca's brutal winter) and there are plenty of nice winter insects to find around here. 

One of those is the Gulf fritillary, a butterfly that breeds year-round here. We found several larvae of various stages on passions vines along the Ohlone Greenway Trail today. There were also many empty pupae on dead vines, and even one that appeared to still be alive. It's actually quite shocking how common this species is around here now despite that it has only arrived in California within the past couple of decades. The larvae are especially easy to find at this time of year, perhaps due to the low parasitism and predation rates during this season, and also perhaps because the winters are considered the "wet"' seasons here. In the summer, a better bet is to look for eggs or catch wild females to lay eggs. 

It's interesting to note the striking difference in coloration between summer and winter larvae. Larval coloration in Lepidoptera often seems to be dependent on the environment they are in. We've seen with several species that the larvae typically manifest a darker, or more melanic, coloration in cold weather and brighter coloration in hot weather, which can be seen in the Gulfs as well. These winter larvae that we collected today are primarily grey with only thin, poorly developed pale orange stripes. It is the opposite in summer, as they are primarily bright reddish-orange with thin grey stripes. ​

We are currently rearing the larvae in petri dishes with passion cuttings and are hoping they'll grow to a reasonable size before we fly back to Ithaca. If not, we'll probably have to put them on the potted passion vine in our yard and cage it up. 

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Authors
Alan Liang

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