6 METHODS OF INSECT LIFE. 



Some knowledge of the method of respiration as well 

 as of circulation in insects is very requisite to agricul- 

 turists for practical purposes, for if the breathing-pores 

 are choked the insect dies. The fact of the head of 

 the insect being free is of no service, for the chief use 

 of the head is for feeding or seeing with ; but if the 

 caterpillar or insect is so treated by being turned out. 

 from its natural home, or by being covered with any 

 sticky dressing that its breathing-pores are choked, it 

 dies ; and in this way we can act on some of our crop 

 pests. 



Metamorphoses or transfoi'mations of insects. — In the 

 case of most animals, or at least of the higher orders 

 of the animal creation, we find that there is commonly 

 a marked difference in each instance, whether it be, 

 say, a horse, or whether it be a chicken, between its 

 shape and external appearance, as well as its internal 

 organs, in its early life, and in its mature state. But 

 there is this noteworthy difference between this method 

 of growth and that of insect life, that whereas with 

 many animals the alteration goes on so gradually, 

 from birth to mature life, that we do not see any 

 sudden change ; in the case of insects the change of 

 appearance is often very rapid. The alteration itself 

 goes on gradually, but from the moult of the skin (such 

 as that of the caterpillar showing the chrysalis within 

 it) frequently taking place in a very few minutes, the 

 difference in appearance of the insect is often, to those 

 not used to the matter, most astonishingly sudden, 

 and gives rise to all kinds of unfounded ideas. These 

 changes, which happen according to regular laws, are 

 what are known as the '' metamorphoses,'' or "trans- 

 formations " of insects, because the insect is then, as 

 it were, "metamorphosed" or "transformed" from 

 one condition to another. 



book of Zoology,' Eng. trans., Ed. of 1880, p. 53;} ; there is also much 

 serviceable (Inscription of the vessels and mode of circulation in 

 Newman's ' History of Insects,' pp. 188 — 191. 



