THE INSECTS OF NEW JERSEY. 21 



was left free. The highest specialization was reached when all 

 three of the thoracic segments united to form a compact body 

 supporting all the organs of locomotion. These modifications, 

 once started, tended to become intensified, and there is little 

 difficulty now in recognizing the orders belonging to each series. 



Perhaps the simplest type in general structure are the Isop- 

 tera, including- what are generally known as Termites or white 

 ants. They are soft-bodied, loose-jointed, all the thoracic rings 

 well developed and altogether primitive in appearance. The 

 wings are large and frail, net-veined, not united in flight and not 

 folded when at rest. Yet, while these insects retain their primi- 

 tive structure, they have become very highly specialized socially, 

 living in immense communities with specialized worker, soldier 

 and other castes. The workers are blind, never become winged, 

 and even the sexually-mature winged forms have no resting 

 stage; the metamorphosis is incomplete. 



The Mallophaga are the biting lice, and have the same general 

 form as the Termite workers except that they are more flattened 

 and are adapted to their parasitic mode of life. Wings are never 

 developed, the metamorphosis is incomplete, and the insects most 

 commonly infest birds. 



The Corrodentia mark yet another step in advance, but are 

 still soft-bodied and loose-jointed. The book-lice found in 

 houses are a common type, and resemble the biting lice in form ; 

 but they are very active and run rapidly. Some forms develop 

 wings, which are peculiarly veined and not folded when at rest. 



The Neuroptera, including Aphis lions and Ant-lions, are yet 

 further specialized. The larvae retain the Termite worker type, 

 but are more oval and the jaws are much larger and character- 

 istically developed for a predatory mode of life. The larvae, 

 when full grown, form true pupae, which remain quiescent until 

 the adult emerges, and the metamorphosis is thus complete. The 

 adults have, generally, long, slender bodies, with large \vings, 

 which are laid flat when at rest and not folded. This is by far 

 is very compact, the constriction between head and thorax is very 

 is very compact ; the constriction between head and thorax is very 

 well defined, and, altogether, the resemblance to some of the 

 types of the third series is strongly marked. 



