182 NATURE STUDY REVIEW [8 :5— May, 1912 



1. Fore legs held forward in a grasping position. 

 a. Body broad and flat. 



(1.) About 2'i inches long and 1\ inches broad. 



Larger Giant Water Bugs (Fig. 9). 

 (2.) A little less than one inch long. 



Smaller Giant Water Bugs (Fig. 10). 

 h. Body long and narrow; a long slender breathing tube on the end 

 of the abdomen. Water Scorpions (Fig. 13). 



2. Fore legs not held forward in a grasping position. 

 a. Front wings soft and membranous. 



(1.) The back is shaped like the bottom of a boat and the insect 



swims upside down. Backswimmers (Fig. 15). 



(2.) The back is flat and the insect swims right side up. 



Water Boatmen (Fig. 14). 

 h. Froiit wings thick and horny. 



(1.) Fringe on the hind legs only; color black with the sides bor- 

 dered with yellow. Diving Beetles (Fig. 12). 

 (2.) Fringe on the second and third pairs of legs; color black, no 

 yellow margins. Water Scavenger Beetles (Fig." 11). 



II. Immature Insects. 



A. Insects usually with wings showing as little pads on the thorax, 

 Nymphs. 



(1.) With long bristles on the end of the body. 



a. Two bristles on the end of the body; tufts of thread-like gills at 

 the bases of the legs. Stone Fly Nymphs (Fig. 16). 



h. Two or three bristles on the end of the body ; flat leaf-like gills 

 on the sides of the abdomen. May Fly Nymphs (Fig. 17). 

 2. No bristles on the end of the body, 

 o. Three broad leaf-like plates on the end of the body. 



Damsel Fly Nymphs (Fig. 20). 



b. No leaf-like plates on the end of the body. 



Dragon Fly Nymphs (Fig. 4). 



B. Insects with no wing pads on the thorax, Larvae. 



1. Without true jointed legs. 



a. Attached to rocks, twigs, leaves or grass in rapidly running water. 



Black Fly Larvae (Fig. 19). 

 h. Not attached. 



(1.) Thorax larger than the remainder of the body, 

 (a.) End of the body forked; head smaller than the thorax. 



Mosquito Larvae (Fig. 2). 

 {h.) Two flaps on the end of the body; thorax and head very 

 large. ]\1osquito Pupae (Fig. 3). 



(2.) Thorax not different from the remainder of the body, 

 (a.) Color red; I to ?s of an inch long. 



Blood Worm [Chironomous larvae (Fig. 26)]. 

 (t>.) Color dirty white or brown; 1 to 2 inches long. 



Crane Fly Larvae (Fig. 24). 



2. With true jointed legs. 



a. Living in a case covered with little stones, small twigs, or various 



kinds of debris. Caddice Fly Larvae (Fig. 25). 



b. Not living in a case. 



(1.) With tapering projections on the aI)domen. 



(a.) 2 to 2i inches long. Dohson Fly Larvae (Fig. 23). 

 lb.) Less than 1 inch long. Wihrligig Beetle Larvae (Fig. 18). 

 (2.) No projections on the abdomen. 



(o.) Abdomen slender; no teeth on the strong javv>;. 



Water Tigers [Diving Beetle larvae (Fig. 21.)] 

 (&.) Abdomen rather plump; teeth on the jaws. 



Water Scavenger Beetle Larvae (Fig. 22). 



