level, were simply plagued with it. The prevailing winds during the
summer are from the south and mosquitoes cannot fly a foot against the
wind, but will fly hundreds of yards, and even the best part of a mile,
with it. The well-known seasonal preference of the disease for warm
spring and summer months, and its prompt subsidence after a killing
frost, were seen simply to be due to the influence of the weather upon
the flight of mosquitoes. Shakespeare's favorite reference to "the sun
of March that breedeth agues" has been placed upon a solid entomological
basis by the discovery that, like his pious little brother insect, the
bee, the one converted and church-going member of a large criminal
family, the mosquito hies himself abroad on his affairs at the very
first gleam of spring sunshine, and will even reappear upon a warm,
sunny day in November or December. Perhaps even some of the popular
prejudice against "unseasonable weather" in winter may be traceable to
this fact.

Granted that mosquitoes do cause and are the only cause of malaria, what
are you going to do about it? At first sight any campaign against
malaria which involves the extermination of the mosquito would appear
about as hopeless as Mrs. Partington's attempt to sweep back the rising
Atlantic tide with her broom. But a little further investigation showed
that it is not only within the limits of possibility, but perfectly
feasible, to exterminate malaria absolutely from the mosquito end. In
the first place, it was quickly found that by a most merciful
squeamishness on the part of the plasmodium, it could live only in the
juices of one particular genus of mosquito, the _Anopheles_; and as
nowhere, not even in the most benighted regions of Jersey, has this
genus been found to form more than about four or five per cent of the
total mosquito population, this cuts down our problem to one-twentieth
of its apparent original dimensions at once. The ordinary mosquito of
commerce (known as _Culex_) is any number of different kinds of a
nuisance, but she does not carry malaria.

Here the trails of the extermination party fork, one of them taking the
perfectly obvious but rather troublesome direction of protecting houses
and particularly bedrooms with suitable screens and keeping the
inhabitants safely behind them from about an hour before sundown on. By
this simple method alone, parties of explorers, of campers, of
railroad-builders going through swamps, of the labo