32 



PARASITES OF THE DOMESTIC ANIMALS 



short eleven-segmented antennae, no single eyes, broad wings, and stout 

 legs. Only the females are provided with piercing mouth parts. 



The larvae, so far as known, are aquatic. The eggs are deposited in a 

 compact layer upon some object, usually rock, near the surface of a 

 flowiiig stream. Upon hatching the larvae drop into the stream and live 

 attached to sticks, stones, or other objects under the surface of swiftly 

 running water. They may detach themselves and move about in a 

 looping manner similar to that of the measuring worm, or they may 

 be carried by the current for considerable distances. Respiration is 

 carried on by gill-like processes. 



SiMULIUM PeCUARUM 



The Southern Buffalo Gnat (Fig. 17). Simuliidae (p. 31). The adult 

 female is nearly a quarter of an inch in length, the male somewhat 



smaller. The color of the body is 

 black, and it is covered with light 

 brown hairs which are arranged upon 

 the thorax in such a manner as to give 

 a longitudinal striped appearance, the 

 abdomen showing upon its dorsal side 

 a broad grayish stripe widening out 

 toward the abdominal apex. The 

 male notably differs from the female 

 in that the eyes are much larger and 

 join each other in the middle line. 

 The individual facets on the' upper 

 part of the eye are considerably larger 

 than those of the female. 



The larva (Fig. 18) agrees in gen- 

 eral appearance with that of other 

 species of Simulium. It is about 

 three-eighths of an inch in length, 

 twelve-segmented, somewhat con- 

 stricted in the middle, enlarging to- 

 ward both ends. The posterior end 

 is the larger and is somewhat club- 

 shaped. In addition to the mouth, 

 the head possesses two fan-shaped bodies which are prehensile in func- 

 tion. On the top of the last abdominal segment there are rows of 

 booklets, while in the vicinity of the rectum are organs of respiration 

 consisting of three tentacles to which the large tracheae lead. 



The pupa (Fig. 19) has a peculiar tuft of respiratory filaments starting 

 from each side of the thorax. The upper portion of the pupal case is 

 open, exposing the head and permitting the respiratory filaments to 



Fig. 17. — Simulium pecuarum, female 

 — enlarged (after Osborn, Bui. No. 5, 

 Bureau of Entomology, Dept. of Agr.). 



