Page:Popular Science Monthly Volume 79.djvu/435

Rh

T is universally admitted that economic entomology, like such other branches of applied biology as medicine and sanitary science, is to a very considerable extent the strategics of our warfare with a host of parasites, which are forever endeavoring to destroy our bodies, our domestic animals, our food supply, our clothing and the very materials with which we construct our dwellings and on which we write or print our interpretations of the wonderful world in which we live. In other words, economic entomology is, to nearly all intents and purposes, merely that portion of applied parasitology which deals with insects. Naturally, therefore, the destruction of the insect parasites of man and of the plants and animals on which his very existence depends, must always constitute the basic interest of this science.

A vague notion of putting certain of the parasites themselves to some use in the struggle to which I have referred, seems to have been apprehended even in pre-scientific times and among primitive peoples. We have read of savage tribes, which, like monkeys, eat their hexapod ectoparasites. The Aztecs invented another use for these creatures, as we learn from a quaint work published many years ago by Cowan. He cites the following story from Torquemada "respecting the revenue of Montecusuma which consisted of the natural products of the country, and what was produced by the industry of his subjects. During the abode of Montecusuma among the Spaniards, in the palace of his father, Alonzo de Ojeda one day espied in a certain apartment of the building a number of small bags tied up. He imagined at first that they were filled with gold dust, but on opening one of them, what was his astonishment to find it quite full of lice? Ojeda, greatly surprised at the discovery he had made, immediately communicated what he had seen to Cortes, who then asked Marina and Anguilar for some explanation. They informed him that the Mexicans had such a sense of their duty to pay tribute to their monarch that the poorest and meanest of the inhabitants if they possessed nothing better to present to their king, daily cleaned their persons, and saved all the lice they