72 dkagon flies \s. mosquitoes. 



3. Pupa. 



6. Conditions favorable to formation of pupge. 



7. Conditions favorable to pupal existence and maturity. 



4. Imago. 



8. Conditions favorable to perfection of imago. 



9. Conditions under which imago will partake of nour- 

 ishment. 



These conditions vary generally in the same ratio as 

 the number of transformations, and are frequently want- 

 ing in the transformations themselves ; each insect is in 

 fact sui generis as respects these conditions, which can 

 only be determined by personal observation. Inasmuch 

 as a failure to satisfy any one of these jjarticulars or con- 

 ditions, so far as they may be requisite to any insect, will 

 defeat the rearing, the elimination of any one of them 

 will operate to destroy ; the result attained being the 

 same, however opposed the intention. 



Bearing these principles and the object to be accom- 

 plished in mind, the discussion of the question may be 

 considered under the following divisions : — 



I. Natural conditions under which the insects in ques- 

 tion breed, with life history so far as applicable or known. 



II. Experiments in rearing in imitation of natural con- 

 ditions. 



III. Habits of insects in question. 

 TV. Relations to each other. 



V. Conclusions. 



