ENTOMOLOGY. 379 



When the time for development has come, the pupa (if it is 

 one of the active forms, as of a Grasshopper, for instance) 

 may be seen looking heavy and stupid ; presently the skin of 

 the back splits lengthwise, and through the opening the 

 perfect insect slowly makes its way out of the pupal skin, 

 carefully drawing one limb after another from its precisely- 

 litting case, the long hind legs the last, till (in the instance 

 observed, in twenty minutes) the perfect Grasshopper stands 

 by the side of the film of its former self. Flies press out one 

 end of the Fly-case, or crack it open, or leave the sheaths of 

 the limbs and body behind, and Beetles and Wasps cast the 

 film from their limbs ; Butterflies and Moths crack open the 

 chrysalis-case, and after a short time (during which the wings 

 that had lain undeveloped are expanding) they appear of their 

 full size. The insect is now fully formed ; it will grow no 

 more ; its internal, as well as external, structure is complete ; 

 and it is what is known scientifically as the imaf/o. 



Imago (Beetle, Butterfly, Wasp, Fly, &c.). — This is defined 

 as an animal formed of a series of thirteen rings or seg- 

 ments, breathing by means of tubes (tracheae) which convey 

 the air from pores in the sides throughout the system, and 

 divided into three chief portions. Of these the first is the 

 head, furnished with horns (antennae), a mouth (differing very 

 much in form in difterent kinds of insects), large compound 

 eyes (which consist of many small ones formed into a convex 

 mass on each side of the head), and frequently two or three 

 simple eyes on the top. 



The second portion (called the thorax, or sometimes the 

 "trunk") is formed of three rings bearing a pair of legs 

 attached to each, and having usually a pair of wings on the 

 second and third of the rings ; but sometimes the wings are 

 wanting, sometimes there is only one pair. 



The third portion (called the abdomen) is formed of the 

 remaining nine rings, and contains the organs of reproduc- 

 tion and most of those of digestion. 



Insects in this perfect state are of two sexes, male and 

 female ; in some instances (as with Wasps and some others) 

 there are imperfection-developed females, known as ''neuters." 



After the insect — whether Beetle, Butterfly, Fly, or other 

 kind — has come from its chrysalis or Fly-case (that is, from 

 the pupa), and its limbs have expanded, it is complete, and its 

 remaining work is to support life until it has propagated its 

 species. Usually pairing soon takes place, and the male 

 dies ; but the female has great tenacity of life until she has 

 laid her eggs. The length of life, however, is various ; in 

 some instances a few days, or even hours, is the extent : in 

 others the insects " hybernate," that is, find some shelter in 



