126 INSECTS INJURIOUS TO VEGETATION. 



wings, when not in use, are folded lengthwise in narrow plaits 

 like a fan, and are laid straight along the top or sides of the 

 back. They are also covered by a pair of thicker wing-like 

 members, which, in the locusts and grasshoppers, are long and 

 narrow, and lie lengthwise on the sides of the body, sloping 

 outwards on each side like the roof of a house; in the cock- 

 roaches, these upper wings or wing-covers are broader, almost 

 oval, and lie horizontally on the top of the back, overlapping 

 on their inner edges ; and in the crickets, the wing-covers, when 

 closed, are placed like those of cockroaches, but have a narrow 

 outer border, which is folded perpendicularly downwards so as 

 to cover the sides of the body also. 



All the Orthopterous insects are provided with transversely 

 movable jaws, more or less like those of beetles, but they do 

 not undergo a complete transformation in coming to maturity. 

 The young, in fact, often present a close resemblance to the 

 adult insects in form, and differ from them chiefly in wanting 

 wings. They move about and feed precisely like their parents, 

 but change their skins repeatedly before they come to their fuU 

 size. The second stage in the progress of the Orthopterous 

 insects to maturity, is not, like that of beetles, a state of in- 

 activity and rest, in which the insect loses the grub-like or 

 larva form which it had when hatched from the egg, and be- 

 comes a pupa or chrysalis, more nearly resembling the form of 

 a beetle, but soft, whitish, and with its undeveloped wings and 

 limbs incased in a thin transparent skin which impedes all 

 motion. On the contrary, the Orthoptera, in the pupa state, 

 do not differ from the young and from the old insects, except 

 in having the rudiments of wings and wing-covers projecting, 

 like little scales, from the back near the thorax. These pupas 

 are active and voracious, and increase greatly in size, which is 

 not the case with the insects that are subject to a complete 

 transformation, for such never eat or grow in the pupa state. 

 When fully gi-own, they cast off their skins for the sLxth or 

 last time, and then appear in the adult or perfect state, fuUy 

 provided with all their members, with the exception of a few 

 kinds which remain wingless throughout their whole lives. 

 The slight changes to which the Orthoptera are subject, con- 



