Mark Melton
Life of the Party
These Ecdyonurus nymphs and their parasites were found in Mill Creek, a tributary of the Russian River. The Symbiocladius parasites are members of Diptera (fly family). I've only found them on Ecdyonurus nymphs although they are also found on Rhithrogena and Paraleptophlebia nymphs as well. They feed off the blood of the nymphs and may prevent them from transforming into adults. The first two photos show Ecdyonurus nymphs without parasites, the following three photos show the nymphs with parasites.