INSECTS. 



245 



process of molting must be repeated. With each of these 

 molts the animal grows more like the adult, the wings 

 appearing first as small pads upon the back (fig. 69), and 

 with later molts attaining the final size. In other words, 

 the Orthoptera are hemimetabolous. It is an easy matter 

 to follow these changes by catching the young hoppers in 

 the spring, and keeping them in a breeding-cage, feeding 

 them frequently with fresh grass and leaves. The student 

 must keep this history in mind v 

 when studying the peculiarities 

 of the beetles. 



With few exceptions the Or- 

 thoptera are injurious to human 

 interests, since they are vegetable- 

 feeders, and, as they often occur 

 in immense numbers, they can 

 destroy all crops throughout large 

 districts. 



Possibly the most disagreeable 

 members of the group are the 

 cockroaches, flattened forms, 

 many of them wingless, which are 

 familiar from the persistence with 

 which they haunt our dwellings, 

 etc., after they have once been 

 introduced. Our familiar ' Croton 

 bug' is an immigrant from 

 Europe, but we have also our 

 native species. Insect-powder 

 and eternal vigilance are the 



.-..,, FIG. 70. Tropical walking- 



only means known to rid a build- stick (Acanthodems}. From 



Hertwig. 



ing of these pests. 



Strangest of our Orthoptera are the 'walking-sticks'; 



