ORTHOPTERA. 199 



first devouring the vegetation in particular fields and patches in the vicinity of their 

 birthplaces, they gradually widen the area of their devastation, until at last, if very 

 numerous, they devour every green thing over extensive districts. Whenever they 

 have thus devastated a country they are forced to feed upon one another, and j)erish in 

 immense numbers from debility and starvation. Whenever timber is accessible they 

 collect in it, and after cleaning out the underbrush, feed upon the dead leaves and 

 bark. A few succeed in climbing up into the rougher-bark trees, where they feed upon 

 the foliage, and it is amusing to see with what avidity the famished individuals below 

 scramble for any fallen leaf that the more fortunate mounted ones may chance to 

 sever. This increase in destructiveness continues until the bulk of the locusts have 

 undergone their larval moults and attained the pupa state. The pupa, being brighter 

 colored, with more orange than the larva, the insects now look, as they congregate, 

 like swarms of bees. From this time on they begin to decrease in numbers, though 

 retaining their ravenous propensities. They die rapidly from disease and from the 

 attacks of natural enemies, while a large number fall a prey, while in the helpless con- 

 dition of moulting, to the cannibalistic proclivities of their own kind. Those that 

 acquire wings rise in the air during the warmer parts of the day, and wend their way 

 as far as the wind will permit, toward their native home in the northwest. They 

 mostly carry with them the germs of disease or are parasitized, and whenever they 

 settle do comjjaratively little damage." 



The larva upon leaving the egg and before shedding the amnion has the body soft 

 and flabby ; but as soon as this is shed it hops quite actively. " Belonging to an order 

 in which the transformations are incomplete, the young locust differs but little in gen- 

 ei-al structure from its parent. The most striking differences are the want of wings, 

 and the less flattened, narrower prothorax, which rises from the sides more in the shape 

 of a roof. The abdomen is also more roof-shajaed. The perfect winged form is grad- 

 ually assumed through a series of five moults, at the first four of which the wing-pads 

 become more and more apparent, and at the last of which, from the pupa to the per- 

 fect state, the thorax becomes flattened, full wings are acquired, and the insect ceases 

 to grow, except as the female abdomen becomes gravid and heavy with eggs. Yet 

 with each moult, aside from the colorational changes, certain ininute and less striking 

 structural changes invariably take place, by observing which we may always know the 

 comparative age and the particular stage of growth of any individual." 



Like all creatures which suffer exuviation or the shedding of skin, our locust quits 

 feeding for a while and remains quiet during the process. The first three or larval 

 skins are almost invariably shed on or near the ground, the young insects congregating 

 under grass in little hollows or depressions, or under any shelter that offers for the 

 purpose. The cast-off exuviae are often very abundant in such sheltered places, and 

 are not infrequently mistaken for dead locusts. The last two or pupal moults, on the 

 contrary, more often take place above ground, the insects at these stages of growth 

 preferring to fasten to some elevated object. Immediately after each moult the whole 

 body is soft and colorless, as it was immediately 'after hatching. 



" In order to illustrate the interesting process of moulting, we will trace an individ- 

 ual through the last moult — from the pupa to the winged insect — as it is the most 

 difficult and, on account of the larger size of the animal, most easily watched. The 

 other moults are very similar in mode of execution. 



" When about to acquire wings the pupa crawls up some post, weed, grass-stalk, or 

 other object, and clutches such object securely with the hind-feet, which are drawn up 



