TRANSFORMATION OR CHANGES OF INSECTS. 215 



A butterfly or beetle lays its eggs ; in due 

 time from these eggs a caterpillar or grub, with a 

 ferocious appetite, crawls forth, living for a time, 

 to change into a chrysalis, which in its turn 

 changes into the perfect insect. And so the trans- 

 formation goes on. Perfect insect, egg, larva, 

 pupa, round to imago, or perfect insect again. 



imago 

 J^ Tk 



egg pupa 



^ larva -* 



Small wonder that the old naturalists, not 

 knowing as much as we do, thought that a com- 

 plete transformation of one form of life into 

 another form of life took place, a transformation 

 as startling as though a serpent changed into a 

 bird. 



But our microscope, and hard-working students 

 of science, have taught us very differently now. 

 These transformations are not breaks, but so 

 many changes, or seeming pauses, in the develop- 

 ment of one and the selfsame insect. 



An insect life is generally divisible into four 

 well-marked stages, and the change from one 

 into the other appears to be quite abrupt. But 

 in reality it is not so. 



The whole alteration from the egg to the 

 larva, to the pupa, and then to the imago, or 

 perfect insect, takes place not suddenly but very 

 gradually. 



