Druid flies are typical-sized and -shaped flies, with some atypical behaviors and flourishes.

Clusia occidentalis is the brightly-colored druid fly that I’ve seen at Mount Pisgah in early May. Like others in the family, it has a globular enlargement on the third segment of its antennae and shadowy markings on its wings. 

Males in the family are among the few insects that exhibit lekking. Lek is the Swedish word for play, and as it relates to animal behavior, it refers to the dances and displays males perform as courtship rituals. 

Druid fly males gather at a lek site, usually a dead branch or trunk, and establish dominance by waving their wings and facing off. Scientists think some species may butt up against each other, as they have enlarged heads or antlers. 

As seen in the photo, males look to be smaller than their mates. Females lay eggs under the bark of dead or dying trees, mostly hardwoods but some species use conifers. 

Larvae grow up inside those dead and dying trees, and some are carnivores. Interestingly, druid fly larvae are able to jump!

Warning: If you Google “druid fly” you’ll find links to many sites about World of Warcraft characters. 

Stay curious!

See more of Karen’s work here.


Research article on lekking behavior: https://ijbpsa.com/sites/default/files/IJBPSA-2023-0050.pdf. Accessed 5/3/24.

Wikipedia entry: https://en.wikipedia.org/wiki/Clusiidae. Accessed 5/3/24.