16 DESTRUCTIVE INSECTS OF VICTORIA; 



this will soften the gummy coating- just mentioned, and 

 the limbs of the future butterfly will be seen. In some 

 cases the change takes place (as with various kinds of 

 flies) in the hardened skin of the maggot, which may be 

 called a "fly case"; and in some (as with plant-bugs, 

 aphides, grasshoppers, dragon-flies, and some others) this 

 state of pupa is an active one, in which they move and 

 feed, and resemble the perfect insect, excepting in having 

 more or less rudimentary wing-cases. 



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 liml) after another from 

 its precisely-fitting 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 leave the 

 sheaths of the limbs and body behind. Beetles and wasps 

 cast the film from their limbs; and butterflies and moths 

 crack open the chrysalis case, and after a short time (during 

 wdiicli 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 know^n 

 scientifically as the imago. 



Imago. — Beetle^ Butterfly^ Wasp^ Fly^ S^c, 



This is defined as an animal formed of a series of 

 thirteen rings or segments, breathing by means of tubes 

 (trachea) which convey the air from pores in the sides 

 throughout the system, and divided into three chief por- 

 tions. Of these the first is the head, furnished with horns 

 (antennae), a mouth (diftering very much in form in 

 diflPerent 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. 



