INSECTS AND OTHER SMALL ANIMALS 295 



fourth, the imago stage, which is the fully developed 

 insect. 



Some insects pass through all the stages mentioned, 

 while others omit the pupal stage, the one correspond- 

 ing to the larva then being called a nymph ; and still 

 others both the larval and the pupal stages ; in which 

 cases they are said to pass through incomplete meta- 

 morphosis. 



Insects are classified, according to peculiarities of the 

 wings and other characteristics, into orders. 



Locusts (Orthoptera, straight-winged). --This order 

 has its fore wings straight; its hind wings are gauzy 

 and folded in fanlike plaits. Its members have well- 

 developed jaws and powerful legs. The metamorphosis 

 is incomplete, the larval and the pupal stages being 

 wanting. To this order belong locusts, grasshoppers, 

 crickets, katydids, and cockroaches. The seventeen-year 

 locust is not a true locust and does not belong here. 



The Rocky Mountain or Migratory Locusts. Since 

 the time of Pharaoh locusts have been feared by 

 mankind. When the crops are ripening, locusts some- 

 times appear in swarms, sparing nothing that is green, 

 often destroying the entire crops of sections over which 

 they pass. In the seasons of 1874-1876 the losses sus- 

 tained from this pest were over $50,000,000. 



The locust appears in small numbers every summer, 

 but its natural enemies and the unfavorable conditions 

 for the development of the insect from the egg keep it 

 from being a great pest. It is probable also that the 

 cultivation of large areas of the western country, and 

 fall plowing, will destroy the eggs so that it may never 

 again pass over large areas of country, causing complete 

 devastation. 



