Coelopa vanduzeei

Kelp Fly

Coelopa vanduzeei

Order: 

Diptera

Family: 

Coelopidae

C. vanduzeei is one of the largest flies found on the sandy beach. Their body size ranges greatly, from 4.0mm to 8.5mm. Their black bodies are hunched and lack hairs on the thorax, though their legs are heavily spined. They typically move in groups and can be seen in massive densities from Ellwood Beach to Goleta Beach. Spring and summer months have the highest occurrence, though they can be found year-round. These flies are the most common next to F. rufitibia, and are a significant source of kelp removal on the beach – as larvae. Their larvae are predated on by predatory beetles such as T. pictus, H. crassus, Cafius species, and shore birds, serving as an important resource in the sandy beach food web. Adult flies are also predated on, and possibly feed on fluids or bacteria on kelp and bird feces.