The mantids—of which a common species in the Southern States is known as "mule killers" because of the superstition that its saliva poisons stock—and the gaunt "walkingstick" insects that mimic twigs so well that they are not seen as often as they might be, introduce us to the great tribe of grasshoppers or locusts—two words that it has worried bookmakers to keep straight. The grasshoppers fall into two families, distinguished among other points by the length of the antennæ. The short-horned ones (Acrididæ) are properly called locusts, and the long-horned family (Tetigonidæ) are better known as grasshoppers, despite the fact that until recently the books called this family Locustidæ. To the Acrididæ belong the locusts that in years past have worked such havoc now and then in the West, when vast swarms came from the Rocky Mountains to the new farms along the eastern border of the plains, and ate up the young grass and crops, leaving the ground looking as if swept by fire. It is a story older than written history in all plains districts of southern Asia, Asia Minor, Egypt, and northern and south-central Africa, where no earthquake, or tornado, or other reaction of nature against man's interference with natural conditions, is so dreaded as a visitation of migratory locusts. In this country any such "plagues" as half ruined Kansas forty years or so ago need no longer be anticipated, because the plowing on ranches and other disturbance of the ground in which the locusts lay their eggs is now so extensive, and the methods of checking small flocks are so well understood, that the vast surplus generations that constituted a migration in search of food in the old days are no longer born.