Caption: Black fly pupa (Simulium hippovorum). Pupae are encased in a silk cocoon attached to vegetation or other objects in the water. This species has boot-shaped cocoon, with a raised collar in the front. Note the tentacle-like structures, called pupal gills, coming from the anterior region of pupa. These gills are the respiratory organs for the pupa. Loops of silk often surround the gills. These loops of silk may help create miniature eddies around the gills to aid respiration. S. hippovorum has a pair of gills with eight filaments each. They are designed to extract oxygen both in and out of the water. This helps the pupae survive if water levels fluctuate and the pupa is left above the water line. Simulium hippovorum is a blood-sucking insect closely related to mosquitoes. Black flies are considered a human pest in some areas of the US and Canada. Adult females of certain species are fierce biters, whereas others are strictly a nuisance by their presence around exposed skin areas. Female black flies require a blood meal; males feed mainly on nectar. Adult black fly females lay their eggs in slow moving waters. Larvae emerge from eggs and attach themselves to aquatic vegetation and rocks. Also shown is the prothoracic proleg is used to pull or hold threads of silk, as well as to grasp the silk pad it forms on a substrate in moving water. Most black fly larvae are filter feeders. A head fan sweeps food material into the mouth. Larvae pass through six instar stages before reaching the pupal stage. Pupae are encased in a silken cocoon attached to vegetation or other objects in the water. Adults emerge from the pupal case through a slit in the pupal cuticle and float to the surface on a bubble of air. Black flies can transmit filarial worms to humans resulting in a disease called onchocerciasis, which cause blindness. They may also be potential transmitters of encephalitis.
Magnification*: x4.5
Type: SEM
Copyright 2006 Dennis Kunkel Microscopy, Inc.
Keywords: 07.01.06,black fly,black fly pupa,black fly pupae,blackfly,buffalo gnat,buffalo gnats,fly,gill,human disease,human pest,insect,insect cocoon,insect vector,insects,invertebrate,invertebrates,onchocerciasis,pupa,pupa gills,pupae,respiration,respiratory organ,SEM,silk cocoon,Simulium ,Simulium hippovorum,turkey gnat,turkey gnats,26328C