About This Project

The seaweed fly Fucellia thinobia swarms visitors as they arrive at Alcatraz and the Farallon Islands. This species is thriving in cormorant colonies and their guano-rich habitats. Yet not a single voucher specimen has ever been officially documented in California’s collections! My project will survey for this species, deposit voucher specimens at the UC Davis Bohart Museum of Entomology, and sequence tissue samples to create the first genetic record.

Ask the Scientists

What is the context of this research?

I first encountered Fucellia thinobia as a tickling sensation on my face and legs while observing cormorants from a boat approaching the Farallon Islands. The island manager told me the swarming insects were “corm flies,” laying eggs on dead cormorants for their young to hatch in the nutrient-rich guano underneath. Outside of this encounter, I found only a single reference to the species, an online anecdote from entomologist Robert Kimsey, who confirmed the species’ association with cormorants on Alcatraz Island. F. thinobia has no representation in voucher collections or DNA libraries that I can find. Its family, Anthomyiidae, plays key roles in nutrient cycling and wrack decomposition, but corm flies remain unstudied. Without specimens or sequences, their existence in California ecosystems is effectively invisible. Documenting, archiving, and sequencing F. thinobia will fill this gap.

What is the significance of this project?

A fascinating fly that thrives in guano and carrion around a keystone species remains scientifically invisible. Documenting the previously unstudied Fucellia thinobia is significant in many key ways. It will expand our understanding of how these flies contribute to cormorant colonies, shoreline ecology, and nutrient cycling. This work opens the door to answering future questions about avian pathogen prevention, environmental nutrient pathways, carrion decomposition, cormorant life cycles, and even impacts of climate change. It will also strengthen biodiversity monitoring by generating reference sequences needed for eDNA surveys. Ultimately, this project adds an overlooked (yet difficult to ignore) insect to California’s biodiversity inventory, linking insect diversity to seabird conservation and ecological management of the Farallon Islands and beyond.

What are the goals of the project?

This project will document Fucellia thinobia by collecting voucher specimens from the Farallon Islands and Alcatraz, focusing on shoreline wrack and seabird colony sites where the flies are abundant. Funding will cover field costs and preservation supplies, ensuring specimens are archived in a recognized museum collection, along with tissue aliquots for downstream genetic analysis. The specimens will be sequenced through the California All Taxa Biodiversity Inventory, generating DNA barcodes that can be integrated into statewide databases. Fieldwork will take place November 2025 during scheduled USFWS access to the islands, with museum deposition and sequencing completed immediately afterward. The outcome will be permanent voucher records and genetic data for F. thinobia, making this species accessible to biodiversity monitoring and seabird-associated ecosystem research for the first time in California.