Simuliidce, or Black Flies 
107 
materials which will make the densest and most stifling smoke, are 
often preserved for this use in the spring. Smudges are built in 
pastures for the protection of stock, and are kept burning before the 
doors of bams and stables. As the black-flies do not readily enter a 
dark room, light is excluded from stables as much as possible during 
the gnat season. If teams must be used in the open field while gnats 
are abroad, they may be protected against the attacks of the gnats by 
applying cotton-seed oil or axle grease to the surface, especially to the 
less hairy parts of the animals, at least twice a day. A mixture of oil 
and tar and, indeed, several other preventives, are of practical use in 
badly infested regions; but no definite test or exact comparison has 
been made with any of them in a way to give a record of the precise 
results.” 
‘‘It is easy to drive the flies from houses or tents by burning 
pyrethrum powder inside; this either kills the flies or stupifies them 
so that they do not bite for some time thereafter.” * * * ‘‘Oil of 
tar is commonly applied to the exposed parts of the body for the pur¬ 
pose of repelling the insects, and this preparation is supplied by the 
Hudson Bay Company to its employees. Minnesota fishermen 
frequently grease their faces and hands with a mixture of kerosene 
and mutton tallow for the same purpose.” We have found a mixture 
of equal parts of kerosene and oil of pennyroyal efficient. 
Under most circumstances very little can be done to destroy this 
insect in its early stage, but occasionally conditions are such that a 
larvicide can be used effectively. Weed (1904), and Sanderson (1910) 
both report excellent results from the use of phinotas oil, a proprietary 
compound. The first-mentioned also found that in some places the 
larvae could be removed by sweeping them loose in masses with stiff 
stable brooms and then catching them downstream on wire netting 
stretched in the water. 
Chironomidse or Midges 
The flies of this family, commonly known as midges, resemble 
mosquitoes in form and size but are usually more delicate, and the 
wing-veins, though sometimes hairy, are not fringed with scales. 
The venation is simpler than in the mosquitoes and the veins are 
usually less distinct. 
These midges, especially in spring or autumn, are often seen in 
immense swarms arising like smoke over swamps and producing a 
humming noise which can be heard for a considerable distance. At 
