Tree squirrel bot fly, Cuterebra emasculator
Cuterebra emasculator are natural, native parasites that, typically, do not adversely affect the overall health of their hosts: eastern gray squirrels, fox squirrels, and eastern chipmunks.
Newly hatched larvae enter a mucous-lined orifice (mouth, eyes, nose, or anus) or wound of a host. The larvae migrate to the tissue just at the host’s hide and burrow their mouthparts into the host forming swollen, fluid-draining pores (“warbles”) in which the maggots develop. As cold weather approaches, the larvae remove their mouthparts from the host, back out of the warbles, and drop to the ground to pupate.