APHIS. 



sort has been hitherto uniformly named 

 after the individual species or genus of 

 plants on which it feeds ; or if that could 

 not be ascertained, that on which it had 

 been found ; for some species are rather 

 uncommon and little known,though others 

 are infinitely too numerous. The aphi- 

 des are sufficiently known by the indiscri- 

 minate term of plant-lice ; they abound 

 with a sweet and grateful moisture, and 

 are therefore eagerly sought after by ants, 

 and are devoured by the larva of coccinel- 

 lac, and many other creatures, or they 

 would become, very probably, more de- 

 structive to the whole vegetable creation 

 than any other race of insects known. If 

 Bonnet was not the first naturalist (as is 

 generally acknowledged) who discovered 

 the mysterious course of generation in the 

 aphides, or, as he calls them, pucerons, 

 his experiments, together with those of 

 his countryman Trembly, tended at least 

 to confirm, in a most satisfactory manner, 

 the almost incredible circumstances re- 

 specting it, that an aphis or puceron, 

 brought up in the most perfect solitude 

 from the moment of its birth, in a few 

 days will be found in the midst of a nu- 

 merous family ; and that if the experi- 

 ment be again repeated on one ot the 

 individuals of this family, a second gene- 

 ration will multiply like its parent; and 

 the like experiment may be many times re- 

 ' peatedwitli the same effect, until at last 

 the progeny becomes barren, unless again 

 impregnated by the male; after which se- 

 venl generations may be again produced 

 without further aid of the male, as before. 

 The history of aphides has also been 

 very copiously treated upon by Dr. Kirli- 

 ardson, in a paper printed in the 41st vol. 

 of the Philosophical Transactions ; and 

 by the late ingenious Mr. Curtis, in the. 

 sixth volume of ih Tr.ui -u-pons of the 

 Linnaran Society. The tenor of Dr. Rich- 

 ardson's remarks is briefly this : the great 

 variety of species which occur in the in- 

 seeis now under consideration may make 

 an inquiry into their particular natures 

 M-i-m not a little perplexing, but by re du- 

 ring them under their proper genus, the 

 difficulty is considerably diminished. \Ve 

 may reasonably suppose all the insects, 

 comprehended under any distinct genus, 

 to partake of one general nature ; and by 

 diligently examining am particular spe- 

 i-ies, may thence gain some insi^lu into 

 tlii nature of all the rest. Withthi 

 Dr. Kichardson chose out of the various 

 sorts of aphides the largest of those found 

 on the rose-tree ; not only as its size makes 

 it more conspicuous, but there are few of 



so long duration. This sort appears ear- 

 ly in the spring, and continues late in au- 

 tumn, while several are limited to a much 

 shorter term, in conformity to the diffe- 

 rent trees and plants whence they draw 

 their nourishment. If, at the beginning 

 of February, the weather happens to be 

 so warm as to make the buds of the rose- 

 tree swell and appear green, small aphides 

 are frequently to be found on them.though 

 not larger than the young ones in summer 

 when first produced. It will be found, 

 that those aphides which appear only in 

 springproceedfrom small black oval eggs, 

 which were deposited on the last year's 

 shoot; though when it happens that the 

 insects make too early an appearance, the 

 greater part suffer from the sharp wea- 

 ther that usually succeeds, by which 

 means the rose-trees are some years in a 

 manner freed from them. The same kind 

 of animal is then at one time of the year 

 viviparous, and at another oviparous. 

 These aphides, which withstand the se- 

 verity of the weather, seldom come to 

 their full growth before the month of 

 April, at which time they usually begin 

 to breed, after twice casting ofi' their ex- 

 uvia, or outward covering. It appears 

 that they are all females, which produce 

 each of them a numerous progeny, and that 

 without having intercourse with any male 

 insect : they are viviparous, and, what is 

 equally singular, they all come into the 

 world backwards. "When they first come 

 from the parent, they are inveloped in a 

 thin membrane, having in this situation 

 the appearance of an oval egg ; these egg- 

 like appearances adhere by one extremity 

 to the mother, while the young ones con- 

 tained in them extend to the other, -uul by 

 that means gradually drag the ruptured 

 membrane over the head and body to the 

 hind feet. During this operation, and for 

 some time after, the fore part of the head 

 adheres, by means of something that is 

 glutinous, to the vent of the parent. Be- 

 ing thus suspended in the air, it soon frees 

 itself from the membrane in which it \\as 

 confined; and after its limbs are a little 

 strengthened, is set down on some tender 

 shoots, and is left to provide for itself 

 In the spring months, there appear on 

 the rose-trees but two generations of 

 aphides, including those which proceed 

 immediately from the last years eggs ; 

 the warmth of the summer adds so much 

 to their fertility, that no less than five 

 generations succeed one another in the in- 

 terval. One is produced in May, which 

 CUM > oh" its covering ; while the months 

 of June and July each supply two more, 



