o on the wing--it is to the destruction of the larvae
that attention should be directed. The larva is a slender organism,
white or gray in color, comprising eight segments. The last of these
parts is in the form of a tube, through which the wriggler breathes.
Although its habitat is the water, it must come to the surface to
breathe, therefore its natural position is head down and tail, or
respiratory tube, up. Now, if oil is spread on the surface of a pool
inhabited by mosquito larvae, the wrigglers are denied access to the
air which they must have. Therefore, they drown, just as any other
air-breathing animal would drown under similar circumstances.

_Best Preventive Measures_

As to the best methods to employ in ridding a country place, or any
other region, of mosquitoes, the directions furnished by Dr. L. O.
Howard, the Government entomologist, who has been a careful student of
the problem since 1867, are of great value:

"Altogether,[3] the most satisfactory ways of fighting mosquitoes are
those which result in the destruction of the larvae or the abolition of
their breeding places. In not every locality are these measures
feasible, but in many places there is absolutely no necessity for the
mosquito annoyance. The three main preventive measures are the
draining of breeding places, the introduction of small fish into
fishless breeding places, and the treatment of such pools with
kerosene. These are three alternatives, any one of which will be
efficacious and any one of which may be used where there are reasons
against the trial of the others."

_Quantity of Kerosene to be Used_

"The quantity of kerosene to be practically used, as shown by the
writer's experiments, is approximately one ounce to fifteen square
feet of water surface, and ordinarily the application need not be
renewed for one month.... The writer is now advising the use of the
grade known as lubricating oil, as the result of the extensive
experiments made on Staten Island. It is much more persistent than the
ordinary illuminating oils.... On ponds of any size the quickest and
most perfect method of forming a film of kerosene will be to spray the
oil over the surface of the water.... It is not, however, the great
sea marshes along the coast, where mosquitoes breed in countless
numbers, which we can expect to treat by this method, but the inland
places, where the mosquito supply is derived from comparatively small
swamps and circumscribed pools