THE GRASSHOPPER'S COUSINS
chance arrival of the next course in his ever unfinished banquet of living fare.
Fig. 47. A mantis from Ecuador with a shieldlike extension of its back. (Length 3⅜ inches)
Some exotic species of mantids have the sides of the prothorax extended to form a wide shield (Fig. 47), beneath which the forelegs are folded and completely hidden. It is not clear what advantage they derive from this device, but it seems to be one more expression of deceit.
Of course, as we shall take occasion to observe later, goodness and badness are largely relativity. The mantis is an evil creature from the standpoint of a grasshopper, but he would be regarded as a benefactor by those who have a grudge against grasshoppers or against other insects that the mantis destroys. Hence, we must reckon the mantis as at least a beneficial insect relative to human welfare. A large species of mantis, introduced a few years ago into the eastern States from China, is now regarded as a valuable agricultural asset because of the number of harmful insects it destroys.
Fig. 48. Egg case of a mantis attached to a twig, Stagmomantis carolina
The mantids lay their eggs in large cases stuck to the twigs of trees (Fig. 48). The substance of which the case is made is similar to that with which the locusts inclose their eggs, and is exuded from the
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