MOSQUITOES AND GNATS 



33 



Fig. 18. — Si- 



have free access to the water. The pupa is firmly attached to sticks, 

 leaves, or other submerged objects. On emerging from the pupal case 

 the fly at once rises to the surface and, expanding its 

 wings as it rims upon the water for a short distance, flies 

 swiftly away. 



Occurrence and Effect. — The buffalo gnat has been 

 found in Alaska and throughout the Eastern United 

 States, but appears in greatest numbers in the South, 

 especially about the mouths of rivers and creeks. During 

 the worst years the whole of the Lower Mississippi Valley 

 as far north as St. Louis may be invaded. 



The attacks by swarms of this bloodthirsty and vic- 

 iously active insect upon southern live stock is a source 

 of serious injury and loss. Cattle and horses will mani- 

 fest the presence of the swarms by frantic efforts to de- 

 fend against the attack, cattle rushing wildly about and 

 horses and mules trying to escape by running away. 

 The most destructive raids of the fly usually occur in 

 the months of March and April. They are exceedingly 

 swift in their flight, darting at their 

 victims in search of a suitable place to muiium pecua- 

 draw blood, and in their bite instilling f"™' .'^"^yf""^"" 

 a poison. Many animals die from ex- born, Bui. No. 5, 

 haustion, combined with the toxic Bureau of Ento- 

 effects of the poison from the bites. "J^^f^' °^p*- °* 

 Bronchitis and pneumonia, resulting 

 from the inhalation of large numbers of the insects 

 from which the exhausted animal becomes totally 

 unable to defend itself, may also contribute to the 

 conditions leading to its miserable death. 



Control. — Outbreaks in heavily infested districts 

 may be lessened in frequency and severity by the 

 clearing out of logs and other debris in the beds of 

 streams, thus reducing the number of objects for 

 attachment of the larvse. Unlike those of the mos- 

 quito, the larvae of Simulium thrive best in swiftly 

 running and well aerated water, therefore the re- 

 moval of any submerged object causing shallow and swiftly moving 

 water reduces the possibilities for breeding at this point. 



Protection. — The black gnat dislikes smoke, therefore, as prevention 

 against its attacks in fields and barnyards, the maintenance of smudges 

 is of value. Other repellents, such as fish oil, oil of tar, or other oleagin- 

 ous and resinous substances, either singly or in combination, are 

 applied to the surface of the body, affording a measure of protection 



Fig. 19. — Simulium 

 pecuarum, pupa — en- 

 larged (after Osborn, 

 Bui. No. 5, Bureau of 

 Entomology, Dept. of 

 Agr.). 



