A raccoon. (Procyon lotor) was observed in a weakened condition for several days at a farm a few miles east of Salisbury, Maryland. It was then caught and held in captivity for a few days. It continued to become weaker and on May 3, 1954, B. Mixon of the Maryland Department of Game and Inland Fish submitted it to us for study. There was no evidence of trauma, either internal or external. The fur was matted over the right hind leg, the inguinal region, and over much of the left hind leg. Inspection revealed the presence of thousands of larvae of the green-bottle fly, Phaenicia sericata, (Meigen}1 actively tunneling in and out of the skin and subcutaneous tissue. Muscle under lying infested skin appeared healthy and untraumatized. A few larvae were in comers of the eyes but none were found in other orifices. Gross and microscopic examination of tissue from the raccoon gave no indication of any acute process which might have led to its moribund condition. James (1947. The flies that cause myiasis in man. U. S. Govt. Print. Off.) and Hall (1948: The blowflies of North America.. Thom. Say Foundation) indicate that P. sericata may vary in virulence, some strains becoming parasitic with an ability to invade healthy tissue. In all probability, the larvae described above hatched from eggs originally laid in a skin wound although no evidence for this was found.