Localities in which Pellagra is Prevalent. 39 



A single pure white larva twenty millimeters long was 

 taken among rocks in the Left Fork of Straight Creek, 

 September 1, 1911. Its body is composed of eleven somites 

 and an additional small terminal segment is cylindrical and 

 tapers toward its extremity. A faint brown band follows 

 the anterior margins of the segments behind the first. At 

 the anterior edge and ventral sides of segments four and 

 five are six tubercles. Succeeding segments, except the two 

 posterior, bear a ring of tubercles, two on the' dorsum, the 

 rest at the sides and beneath. 



HEMIPTERA (TRUE BUGS). 



This order contains members that are generally to be 

 found in either standing or running waters, in which they 

 reside at all periods of their lives, some swimming beneath 

 the surface where they remain much of their lives con- 

 cealed from us. When their surroundings become from any 

 cause unsuited to them, they may, as in the case of the 

 large electric light bugs (Benacus griseus and Belostoma 

 americanum) and of the water boatman belonging to the 

 genus Corisa, leave the water, and fly about in search of a 

 better stream or pond. They are as a consequence often 

 captured about electric lights and even in dwellings on hot 

 summer evenings. The species observed in the Cumberland 

 River and the tributaries are well known to every boy as 

 water striders or water skaters, because of their manner of 

 progression on the surface of water. When pursued they 

 dive and conceal themselves, but soon reappear at the sur- 

 face where they float and row themselves about in a leisurely 

 fashion generally in small schools of from three or four to a 

 dozen. All these insects are provided with beaks, with 

 which they capture and kill other animals upon which they 

 feed. Occasionally the collector receives a severe stab from 

 such species as Naucoris poeyi, when handling water plants, 

 but so far as I know, the aquatic species do not at any stage 

 of their lives deliberately attack man. They are interesting 

 in this connection because of their association with Simulium 

 and other stinging gnats in our waters. 



