Lawson on Aphis AveruB, 267 



from Kingston, on the scattered farms along the Addington Road^ 

 back to the township of Olden, a distance of about fit'ty miles. 

 When we consider that many of the farms referred to are mere 

 isolated patches of clearing in the woods, -widely separated from 

 each other, in some cases by miles of interminable forest and 

 swamp, we see that the diflfusion of this insect is totally indepen- 

 dent of its own limited locomotive powers. In its winged state it 

 is no doubt carried in clouds by the winds, like the seeds of 

 thistles and other winged plants. 



In looking over a general collection of insects, one is struck 

 with the large numbers of species peculiar to certain countries or 

 districts, and which, in spite of their locomotive powers and other 

 means of diffusion, seem to persist in adherence to circumscribed 

 localities. The aphides are of a different character ; those of 

 them which infest cultivated plants may probably, with most truth, 

 be regarded as cosmopolitan, having no special regulating influ- 

 ences that we know of beyond the supply of their food and 

 extremes of climate. They are like the corn weeds that spring up 

 wherever the cereal grains are cultivated, and whose original 

 nativity has been lost. The careful observation of animals and 

 plants of this character, in a new country where settlement is still 

 progressing, is calculated to afford valuable information to the 

 zoological and botanical geographer. 



The wingless aphides found in such numbers during the sum- 

 mer are all females, but some of the females are winged. Re- 

 markable as it may appear, it is nevertheless true, that the females 

 have the power of bringing forth living young, without any inter- 

 course of the sexes. This may be readily observed by enclosing 

 one under a glass, and observing the production of new individuals, 

 which is regarded by naturalists rather as the result of a process 

 of budding than a true reproductive process. Late in the season, 

 when cold weather comes on, males are produced, all being 

 winged ; they are known from the winged females by the absence 

 of the tail-like process at the apex of the abdomen. The sexes 

 pair, the females lay eggs, these may remain dormant and be 

 hatched during the following spring, and the young issuing from 

 them are females, capable of giving birth, as before mentioned, to 

 successive broods of young, in a viviparous manner, in the absence 

 of males. 



The reproduction of aphides thus presents some of the most 

 remarkable phenomena with which naturalists are acquainted, 



