122 THE CANADIAN ENTOMOLOGIST. 



upon this point, a solitary winged specimen was secured and confined in a 

 box in which a sprig of the insect's natural food had been previously- 

 placed to satisfy its wants ; due examination having been made to the 

 intent that nothing in the shape of food or animal life should stand in 

 the way of a fair and impartial test. After the lapse of twenty-four 

 hours, the inside of the box and its contents were examined with a glass 

 of moderate diameter, and a single, newly-born Aphis was discovered 

 fastened to a leaf stalk, in the act of imbibing its juice. 



A further continuance of the feeding process for several days longer 

 was productive of the same positive results. The rate of increase in this 

 species, as shown by these experiments, unlke its European congeners, 

 was proved to be but one a day ; so it is to be seen that the insect does 

 not propagate as rapidly in this case at any rate, as naturalists have 

 asserted. European species, we read, produce at the rate of three, four, 

 and seven a day, according to eminent authorities. As our native Ameri- 

 can species differ in many points from European, in a structural as well as- 

 a functional sense, this difference in the rate of propagation may not be 

 wondered at. From the above facts it does seem that nature has decreed 

 that there shall be both winged and wingless specimens in the spring time, 

 for it seems just to conclude that both varieties are virgin females. But 

 other observations which were subsequently made, seem to foreshadow 

 the existence of males also ; but the evidence upon this point is not of 

 the most positive character, and requires further facts to settle it beyond 

 the shadow of a doubt. 



Having secured similar winged specimens a few days later, they were 

 submitted to a like test, when both positive and negative results were 

 reached. Here was a rather curious and interesting problem for solution. 

 Why some should prove fertile, and others, which in no single particular 

 differed therefrom, so far as could be determined, should manifest a 

 contrary state of affairs was more than could be divined, and this too after 

 frequent experiments had been made. If the latter are males, as their 

 sterility would seem to indicate, the solution is self-evident ; but if of the 

 opposite sex, there can be no adequate key to unlock the problem, unless 

 the principle of excessive nutrition, which seems to account for so many 

 strange things in the vegetable creation, should prove to be it. But even 

 here a doubt arises, as observation has shown me that a succulent shoot 

 produces almost invariably wingless specimens, while a less tender one the 

 opposite variety. As the very existence of the two forms depends upon 



