344 HOUSEHOLD INSECTS 



know of them, are similar in general to the one just de- 

 scribed. So far as we know, all black-flies must have water 

 in which to breed and apparently the water has to be 

 moving. Some species of black-flies breed in small 

 streams and some of them in larger rivers. Some seem to 

 delight in swiftly flowing mountain streams and brooks, 

 while others occur in enormous numbers in the larger and 

 more quiet rivers. Twenty-five species of black-flies 

 have been found in North America and fifteen of these 

 occur in the United States. 



Methods of control. — For protection from black-flies, 

 there are two lines of procedure to follow — driving them 

 away with some form of repellent or destroying the larva? 

 and pupa? in the streams with some insecticide. Campers, 

 hunters, woodsmen, and permanent residents use repellents 

 almost entirely to drive the flies away. Evergreen 

 branches or damp moss or lichens serve very well on a 

 camp fire. These materials produce a thick smudge that 

 drives the flies away. In the Adirondacks, smudges for 

 the home are built very largely of hardwood chips, beech 

 perferably. These are also used at night to drive away 

 mosquitoes. 



Pyrethrum, Persian insect powder, or buhach, is used 

 to drive the flies out of houses and tents. Lugger says it 

 is used in the houses and stores of the Hudson Bay Com- 

 pany for this purpose. A little of the powder is burned on 

 a piece of bark and the fumes either kill or stupefy the 

 tormenters. Planters in the South collect during the 

 year all sorts of materials which will produce a dense 

 stifling smoke. They use leather, dried dung, and old 

 rags and clothing. As soon as the gnats appear, the 

 smudges are started and they are kept up until the insects 



