Localities in which Pellagra is Prevalent. 57 



Simulium, but appears to take a mixed food, consisting of 

 algae as well as insects. 



Ephemeride Larva No. .4. —Several very small larvae, 

 having the same general form as No. 3 were everywhere 

 common in the rapids of the streams. They are generally 

 pale whitish with obscure dusky markings, most of them 

 with a dusky band across the heavily fringed caudal setas. 



Adults from some of these larvae were emerging from 

 the water October 23, 1911, at Pineville, and were found 

 stranded on mud and sand at the edge of the river. The 

 males have singular large cap- shaped eyes meeting on the 

 top of the head and in addition a smaller second eye is 

 present on the side of the head beneath the other. The 

 abdomen is provided with but two seteae. Dried specimens 

 brought home with me measure from two to four millimeters 

 in length, and probably represent several species. 



ODONATA (DRAGON FLIES). 



This group of striking insects is represented by indi- 

 viduals about all fresh waters of this country. The species 

 are not very closely discriminated by the angler and hunter, 

 but every one knows them by the name dragon flies, snake 

 doctors, and mosquito hawks. They are powerful fliers, 

 with enormous eyes and often gaudy colors, which flit back 

 and forth over the water, some species appearing very early 

 in spring, but most of them during the hot weather of July 

 and August. The adults are provided with strong jaws, but 

 never attack large animals of any sort, their prey being 

 small insects which they capture on the wing. No doubt 

 their influence is felt by the small fry of this sort, especially 

 in the immediate neighborhood of streams and pools. They 

 do not so often appear about dwellings, and it may be 

 questioned if they have any special effect on the members 

 of our house-infesting mosquitoes, since these generally 

 breed close about dwellings. 



The young of these showy insects are rather obscure 

 water-frequenting animals, lurking about the bottom, partly 

 buried in mud or rubbish, sometimes clinging to water 



