APHIS, the Puceron, Pant Louse, Vine Fretter, or Blighter, an animal which presents several remarkable aberrations trout the known and accustomed laws of na ture; and has thence been frequent') the subject of ob servation among the most enlightened naturalists.
The Aphis is an insect of the order Hcmiptera of who defines it, Snout inflected, antenn,e seta ceous, wings four erect, or none, legs formed for walk ing ; abdomen provided with two obtuse horns behind, and often a style at the tail. This character, how ever, is not constant, as the learned naturalist con ceives, for there are some species in which the cornicula seem entirely wanting. When present, a transparent mellifluous substance generally distils from them. Se venty-two different species have already been described.
This insect may easily be recognized : it is a small, ugly, deformed looking animal, commonly wanting wings, and huddled together in hundreds, on the plants most familiar to us, so closely, as hardly to admit the point of a pin. It is of a dull and sluggish disposition, moving languidly from the place where it has once taken up its abode, and frequently raising the hind legs on any alarm, which seems its only mode of defence. They are from a line in length to the size of a house fly; and there are varieties in the colour, such as green, brown, and yel lowish, altering somewhat according to the season of the year. They also dwell in the pugositics of leaves, which become distorted from their pernicious attacks, and even within galls. Several species arc covered with a white downy substance, sometimes nearly an inch in length, whose nature is not yet fully understood. The trunk is of a singular structure, being composed of three picces or tubes, which seem to sheath into each other like the slide's of a telescope ; and De Geer conjec tures, that part of it may be retracted into the head. In certain species, it is more delicate than the finest hair, and being of immoderate length, lies along under the belly, and passes beyond the extremity of the abdomen like a tail.
In the same family arc found both winged and apter ous aphides. Reasoning from analogy, the latter should be females, because several kinds of butterflies, and other insects, have females wanting wings ; here, how ever, the females arc both winged and apterous, but the males of some species always have wings. The most
singular phenomenon in the nature of aphides, consists in their mode of propagation. At one time of the year, the same race is viviparous, and at another oviparous ; and by another deviation from the ordinary rule, the feet of the young are in the former case protruded first, al ways marked by peculiarities. The ancients thought that they sprung from the clew ; then they were believed to owe their origin to ants, and later naturalists consider ed each as sufficient to produce its offspring by itself, without the concourse of the sexes. It is true, indeed, that their generation is not governed by the ordinary laws ; for one impregnation of a female apparently serves to transmit the prolific quality to its offspring, even to the tenth in succession, so that each interme diate female will produce its young without the con course of the male.
The credit of this discovery is due to Mr Bonnet. On the 20th of May, he isolated a young aphis which he had seen the mother produce. It changed its skin three times, and on the first of June began to breed. Between that day and the 22d it produced 95 young. On the 6th of May he took the young of an apterous mother, the moment it was produced, and kept it in solitude. It be gan to produce young on the '2 1 s t . Next day he con fined a oung one, immediately when produced, and oh tamed young froin it on the 4th of June. On the same day, he confined this one of the second generation, and, to his great surprise, before being full grown, lie o!)- wined young From it on the 15th of the month. From one of these he obtained a fourth generation, from one of the fourth, a fifth, and one of this produced a sixth generation. All, it is to be observed, were isolated. Some began to breed when only half the size of full grown aphides producing young. These experiments proved, therefore, that aphides generate without copu lation.