Experiments in Destroying Black-Flies 



BY CLARENCE M. WEED 



In certain localities throughout a large part of the United 

 States, black-flies are among the most annoying pests that afflict 

 man and his domestic animals. In some of the Southern states 

 the forms called Buffalo Gnats often cause the death of cattle, 

 horses, and mules to an alarming extent, and at the North the 

 attacks of the northern species are often unbearable. In some 

 of the resort regions of New England these flies are the most 

 vexatious pests that afflict the summer visitor as well as the 

 resident citizen. 



No successful method of exterminating these insects has 

 heretofore been known. The only remedies that have been 

 suggested have been various means of preventing or palliating 

 the attacks of the adult flies. The purpose of this bulletin is 

 to describe some successful experiments in ridding a locality 

 of the pests through the destruction of the early stages in their 

 breeding-places. 



To understand the practical meaning of these experiments,, 

 a brief account of the life-history of these black-flies is neces- 

 sary. The adult flies which annoy man by their attacks go 

 through a series of changes during their growth somewhat 

 similar to those which the mosquito goes through during its- 

 development. The flies lay their eggs upon the rocks in the 

 rapids of small streams, especially at the edges of the rippling 

 water. In a short time these eggs hatch into small larvae that 

 are able to spin a silken web upon the rock to hold them in 

 place. Here they continue to develop until finally they change 

 to pupa?, to emerge a little later as adult flies, often in such 

 numbers that they " drive the fisherman out of the woods, tor- 



