Adults are terrestrial. Adults of both groups are terrestrial. Figure 4 . Note the three leaf-like gills at the end of the abdomen. The last abdominal segment bears a pair of fleshy appendages with hooks.
Adults are terrestrial and resemble small moths.
Note the head and legs emerging from the case on the right side of photograph. Photo courtesy of Ken Fritz. In terms of species, this is the largest and most widespread group of stream insects. Adults are terrestrial and often resemble mosquitoes. Figure 8 .