18 PARASITOLOGY. 



propagate. Houses should be screened. Sleeping 

 rooms may be smoked with pyrethrum. The py- 

 rethrum should be molded into cones and dried. 

 These cones, when lighted, will smoulder for a long 

 time, and give off a pungent odor which does not 

 kill the mosquitoes, but stupefies them, rendering 

 them harmless. 



SiMULiUM Pecuarum (Pecus — cattle, simulo — to simulate.) 



Syiioyiym. — Buffalo gnat. 



History. — Found in the South, along the Mississ- 

 ippi river and its tributaries. Their destructive effect 

 upon animals dates back as far as 1850. 



Description. — A small black fly ; abdomen broad 

 and thick; thorax short, thick and provided with a 

 hump from which it gets its common name, resem- 

 bling the hump of a buffalo. The antennae are com- 

 posed of eleven segments. Its wings are wide and 

 short, and its three pair of legs are thick and short. 



Life Cycle. — The adult flies are found from April 

 until after June. They lay from 5,000 to 10,000 eggs 

 in a compact mass on some object directly over the 

 water's edge. Upon hatching, the larva falls into 

 the water. The larva is composed of twelve joints. 

 It fastens itself to rocks and other objects in the 

 river bed, often loosening its hold and floating in the 

 current till another favorable place is found. The 

 larva is carnivorous. The pupal stage is passed in a 

 tough brown cocoon with the upper part open. This 

 cocoon is fastened to sticks and other objects in the 

 water. 



Animals hifested. — They attack the animals, as 

 horses and cattle, in swarms. By means of their 



