They’re popularly known as March Flies or even Lovebugs, but to the scientist, they’re Bibionids. Jutta Burger PhD, Science Program Director at the California Invasive Plant Council, saw and photographed these individuals in the park on April 14. She says the all-black fly is a male, the one with the red thorax is a female.
These flies tend to swarm, and in other times and places have been known to darken the sky. Here, not so much. Still, there were enough of them to get the Barn Swallows excited. Dozens of these energetic birds swooped circles in the air snatching bugs in mid-flight. Even without birds chasing them, these flies don’t live very long. Some species’ life expectancy, once they emerge from the larval stage, is three days. They may spend every minute of it copulating, even in midair, while sipping nectar from and pollinating flowers. Hence the nickname lovebugs. Sex-obsessed or not, they are important pollinators. The larvae help to compost the soil and create humus. They’re completely vegetarian and don’t bite or sting humans.
There are about 60 species of bibionids in California, and it takes a specialist to distinguish them. They are the most ancient of the flies, with a fossil record possibly extending to the Jurassic.