70 
Applied Entomology 
animal life have died out. He writes : “ When the moon shall have 
faded from the sky and the sun shall shine at noonday a dull cherry 
red, and the seas shall be frozen over and the ice-cap shall have crept 
downward to the equator from either pole, and no keel shall cut the 
waters, nor wheels turn in the mills, when all cities shall have long 
been dead and crumbled into dust, and all life shall be on the last 
verge of extinction on this globe, then, on a bit of lichen, growing on 
the bald rocks beside tbe eternal snows of Panama, shall be seated 
a tiny insect, preening its antennae in the glow of the worn-out sun, 
representing the sole survival of animal life on this, our earth,— 
a melancholy ‘ bug 
It can scarcely be regarded as remarkable that such a dominant 
class of animals should come into direct collision with the operations 
of man. Man has been forced to take into his cognisance the existence 
of such a warfare, and to take measures to ensure against his own 
defeat. Thus has the need for the recognition of applied or economic 
entomology taken birth. It is to be defined as the study of insects in 
relation to the welfare of the human race, and is divisible into three 
branches. 
1. Medical entomology which concerns itself with those insects 
which attack man directly and thereby frequently transmit diseases 
which endanger his life. 
2. Agricultural entomology which is the study of the insects which 
partially or completely destroy crops and forests or harm domestic 
animals. . . 
3. Economic entomology, in the narrowest sense of the term, which 
deals with those insects which attack and destroy stored and manufac¬ 
tured goods. 
II. Medical Entomology. 
It is in connection with disease that insects inflict the most obvious 
direct injury to the human species. When it is reflected that the patho¬ 
genic agents of malaria, yellow fever, plague, sleeping sickness and 
many other virulent diseases are conveyed to man through the agency 
of biting insects, the importance of this aspect of applied entomology 
can scarcely be overestimated. The application of entomology to 
medicine has been crowned with some of the greatest triumphs of 
human ingenuity. It is now a well-known fact that by waging war 
against Anopheline mosquitoes the town of Ismailia has been practically 
freed from malaria. Prior to the discovery of the transmission of 
