d renewed every week during
the summer time, the overflow can be taken care of in a ditch that will
lead it away from the trough to where it will sink into the ground, the
banks of the streams or ponds or lakes can be cleared in such a way that
fish can get to all parts of the water; most of the small ponds can be
drained or their surface may be covered over with a thin film of
kerosene. This is best applied as a spray; one ounce to fifteen square
feet will suffice. If the oil is simply poured over the surface more
will be required.

The fighting of the species that breed on the extensive salt-marshes in
many regions is a larger and more difficult problem, but as it is a
matter that usually concerns large communities, sometimes whole states,
it can be dealt with on a larger scale. The very excellent results that
have been accomplished in New Jersey and on the San Francisco peninsula,
and in a smaller way in other places, show what may be done if the
community goes about the fight in an intelligent manner. In the fight in
New Jersey hundreds of acres of tide-lands have been drained so that
they no longer have tide pools standing where the mosquitoes may breed.
When it is impracticable to drain them the pools may be sprayed
occasionally with kerosene.

The value of the land that is reclaimed by a good system of draining is
often enough to pay many times over the cost of draining, thus the
mosquitoes are gotten rid of and the land enhanced in value by a single
operation.

CHAPTER VII

MOSQUITOES AND MALARIA

Ever since the beginning of history we have records of certain fevers
that have been called by different names according to the people that
were affected. As we study these names and the various writings
concerning the fevers we find that a great group of the most important
of them are what we to-day know as malarial fevers. Not only are these
ills as old as history but they have been observed over almost the
entire inhabited earth. There are certain regions in all countries where
malaria does not occur, but almost always it will be found that other
regions near by are infected and it very often happens that these
infected regions are the most profitable parts of the land, the places
where water is plentiful and vegetation is luxuriant. Indeed the
coincidence of these two things, low-lying lands with an abundance of
water, particularly standing water, and malaria has always been noted
and gave rise to th