96 INSECTS. 



Such as get into the blood may be removed through the 

 secreting action of the Malpighian vessels, or may escape 

 by osmosis directly through the walls of the alimentary 

 canal. 



II. Reproduction. All insects are dioecious; i.e., the 

 sexes are distinct. Paired generative organs are found in 

 the abdomen beneath the dorsal vessel. 



Nearly all insects are produced from eggs. For the 

 few remarkable exceptions, and for the presentation of 

 the interesting questions connected therewith, the student 

 is referred to the larger works on entomology. 



Of the metamorphoses of insects there are two general 

 types: 1. When incomplete, there emerges from the egg 

 a nymph, which differs from the adult principally in size, 

 and which, when grown, transforms directly into a perfect 

 insect ; 2. When complete, the egg produces a larva, 

 usually a little wormlike creature with little external 

 likeness to its parents. This, when grown, transforms 

 into a pupa, which, after a quiescent period, again trans- 

 forms when an imago issues. 



It must be borne in mind that a few transformations 

 will not conform strictly to either of these types, also 

 that there is no difference in kind between the two types. 

 Convenience is the best reason for naming the growing 

 stage of the one nymph, and of the other, larva. 



It must be observed that the growth of the insect is 

 completed during the larval or nymph stage. Eating is 

 the sole business of nymph or larva. But of adults, some 

 do not eat at all, and those that eat to keep alive do not 

 grow. To reproduce their kind, to fulfill their part in 

 Borne one of nature's little groups of diverse forms of life, 

 and perhaps to enjoy their brief existence, seem to be 

 their mission. 



It will be noticed, that of the inhabitants of field, forest, 



