AQUATIC INSECTS OF FRESHWATER 



prominent eyes, filiform antennae, long and full thorax and segmental 

 abdomen. This order is now restricted to a few families in the United 

 States, including the Dobsons or Sialidae, the May- or Shad-flies or 

 Ephemeridae; the Stone-flies or Plecoptera; the Dragon-flies or Odonata; 

 and the Caddice-flies or Trichoptera. 



Dobsons belong to the family of Sialiadse, and include the Fish-flies, 

 Hellgramites, Alder-flies and others of diverse popular names. They have 

 four thin, broad, net-veined wings which are folded when at rest. All 

 are weak flyers with legs scarcely able to support the body. The mouth 

 parts are developed for biting, the abdomen long and slender, the antennae 

 long, the head broad with protruding eyes, and the mandables well developed. 

 Of the Fish-flies or Sialis there are but two species, S. infumata and S. 

 americana, both small insects which frequent vegetation on the banks of 

 streams. The eggs are laid in white cottony masses on plants overhang- 

 ing the water, on bridges, piers, etc., into which the larvae drop when hatched. 



The largest species of Dobson is the Horned Corydalis, C. corinita,which. 

 has a spread of wings of over five inches and is quite generally distributed. 



FIG. III. Hellgramite, larva Xi^ NJCi*^ 



of the Dobson. FIG. 212. Horned Dobson, Corydalis cor'inita. 



The larvae are known as Dobsons, Hellgramites, Bugies, etc., and are exten- 

 sively used as bait for game fishes. They live under rocks and 



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