Localities in which Pellagra is Prevalent. 55 



in the State, are the larvae of fragile, gauzy-winged insects 

 known as May flies. Though holding their own against the 

 current as well as tougher-skinned and more strongly built 

 insects, they do this more by virtue of their expertness in 

 sticking close to the under sides of rocks than by their 

 capacity to swim. They resemble somewhat the stone flies 

 in general appearance, being, like them, provided with 

 slender, tapering antennae and long, jointed, caudal stylets, 

 three in number, however, in well-grown examples, where- 

 as the stone fly young have at all stages only two. They 

 can always be distinguished by the presence of gills, plate- 

 like in all the species collected, along the sides of the 

 abdomen, and by the presence of but one tarsal claw. 

 Adults of small species belonging to this group of insects 

 were emerging October 23, 1911, at Pineviile, and were 

 found in some numbers early in the morning in the mud 

 and sand at the edge of the water, though the temperature 

 at the time was close to freezing. These were doubtless from 

 some of the small larvae, noted farther along under No. 4 of 

 this part of my account. They are slender, pallid, fragile 

 insects, with large membranous front wings and small or 

 minute hind ones. At the end of the body are two long 

 slender setae. The creatures are rather feeble fliers and 

 after mating drop their eggs in the water and soon die. 

 The members of the group are sometimes called day flies, 

 the adults being popularly supposed to live but a day. They 

 do indeed last but a short time, once adult, but live for a 

 year or more in the water. 



Ephemeride Larva No. /. — A common and widely dis- 

 tributed larva of the group was taken in all the mountain 

 streams examined. Its body is flat, the head broad, the 

 outline everywhere rounded. The simple eyes are accom- 

 panied by three pale dots. The series of gills along the 

 sides of the abdomen are terminated by a simple fringed 

 filament behind. The abdominal segments are provided 

 with a strong sharp tooth at each side. The caudal ap- 

 pendages are noticeably setose. The color above is a mixed 

 pattern of black and pale yellow; the legs are banded with 



