Liam O’Brien would like San Francisco to be remembered for more than the first known eradication of a butterfly species from the planet. The Xerces Blue went extinct in the 40s due to urbanization, and possibly because of the popularity of the butterfly in people’s butterfly collections in Victorian times. He would like to see the Green Hairstreak survive on the hills of San Francisco.
Liam took us through the biology and ecology of butterflies and why they can be so susceptible to human interference. Butterflies have host plants on which eggs will be laid, and some species including the Green Hairstreak is very particular (Deer weed and coastal buckwheat). Further, butterflies have a nectar source, and here again the Hairstreak is a picky eater of Wild Cucumber and Seaside daisy.
The butterflies only fly from 8-10 days in March through Mid May. The length of the season depending on the amount of spring rain. The larva sits in leaf litter for months before it pupates. The hairstreak is also one of 15 species in San Francisco that is a hill topper. Around 3pm in the afternoon the butterflies will fly to the top of one of the few hills they congregate looking for a mate. The females then disperse.
In an urban world this is the danger point for butterflies, especially the Green Hairstreak females looking for a spot to lay their eggs.
This where the Project comes in, trying to create corridors of habitat for these little minute creatures. Organizing people to grow and plant the host plants and nectar sources that will allow this “charismatic micro fauna” to survive. In this little project there is now a community of people who are coming together to plant a community of plants that will keep a community of animals.
Hopefully this can be a model for some of our other native species, and in the process bring us back a little of what we have lost. To find out more, check out their page on Nature in the City.
SF Natural History Series 