APHIS. 



which cast oft' their coverings three or 

 four times, according to the different 

 warmth of the season. This frequent 

 change of their outward coat is the more 

 extraordinary, because it is repeated more 

 often when the insects come the soonest 

 to their growth, which sometimes hap- 

 pens in ten days, when they have had 

 plenty of warmth and nourishment. arly 

 in the month of June, some of the third 

 generation, which were produced about 

 the middle of May, after casting off the last 

 covering, discover four erect wings,much 

 longer than their bodies; and the same 

 is observable in all the succeeding genera- 

 tions which are produced during the sum- 

 mer months, but still without any diversi- 

 fy <-i' sex ; for some time before the 

 aphides come to their full growth, it is 

 easy to distinguish which will have wings, 

 by a remarkable fulness of the breast, 

 which in the others is hardly to be dis- 

 tinguished from the body. When the 

 last covering is rejected, the wings which 

 were before folded up in a very narrow 

 compass, are gradually extended in a sur- 

 prising manner, till their dimensions are 

 at last very considerable. The increase 

 of these insects in the summer-time is so 

 very great, that by wounding and exhaust- 

 ing the tender shoots, they would fre- 

 quently suppress all vegetation, had they 

 not many enemies to restrain them. Not- 

 withstanding these insects have a numer- 

 ous tribe of enemies, they are not without 

 their friends, if those may be considered 

 as such, who are officious in their atten- 

 dance for the good things they expect to 

 reap thereby. The ant and bee are of 

 this kind, collecting the honey in which 

 the aphides abound, but with this differ- 

 ence, that the ants are constant visitors, 

 the bee only when flowers are scarce ; the 

 ants will suck in the honey, while the 

 aphides are in the act of discharging it; 

 the bees only collect it from the leaves on 

 which it has fallen. The aphides are often 

 carried home by the ant, carefully attend- 

 ed, and regularly supplied with food. See 

 Formica. In the autumn three more ge- 

 nerations of aph : des are produced, two of 

 which generally make their appearance 

 in the month of August, and the third be- 

 fort the middle of September. The two 

 first differ in no respect from those which 

 are found in summer, but the third differs 

 greatly from all the rest. Though all the 

 aphides which have hitherto appeared 

 were female, in this generation several 

 male insects are found, but not by any 

 means so numerous as the females. The 

 females have, at first, the same appearance 

 as those of the former generations, but in 



a few days their colour changes from a 

 green to a yellow, which is gradually con- 

 verted into an orange before they come 

 to their full growth ; they differ, also, in 

 another respect, from those which occur 

 in summer, for all these yellow females are 

 without wings. The male insects are, 

 however,still more remarkable, their out- 

 ward appearance readily distinguishing 

 them from this and all other generations. 

 When first produced they are not of a 

 green colour like the rest, but of a red- 

 dish brown, and have afterwards a dark 

 line along the back : they come to their 

 full growth in about three weeks, and 

 then cast off their last covering r the whole 

 insect being, after this, of a bright yellow 

 colour, the wings only excepted ; but af- 

 ter this change they become of a deeper 

 yellow, and in a very few hours of a dark 

 brown, if we except the body, which is 

 something lighter coloured and has a red- 

 dish cast. The males no sooner come to 

 maturity than they copulate with the fe- 

 males, who, in a day or two after their in- 

 tercourse with the males, lay their eggs, 

 generally near the buds. Where there 

 are a number crowded together, they, of 

 course, interfere with each other, in which 

 case they will frequently deposit their 

 eggs on other parts of the branches. 

 It is highly probable that the aphides de- 

 rive considerable advantages by living in 

 society ; the reiterated punctures of a 

 great number of them may attract a larger 

 quantity of nutricious juices to that part 

 of the tree or plant where they have taken 

 up their abode. The observations of Mr. 

 Curtis on the aphides are chiefly intended 

 to shew that they are the principal cause 

 of blights in plants, and the sole cause 

 of the honey-dew. He therefore calls 

 them the aphis, or blighter ; and after ob- 

 serving, that, in point of numbers, the in- 

 dividuals of the several species composing 

 it surpass those of any other genus in the 

 country, speaks thus, in general terms, of 

 the whole tribe. These insects live en- 

 tirely on vegetables. The loftiest tree-is 

 no less liable to their attacks than the most 

 humble plant. They prefer the young 

 shoots on account of their tenderness, and 

 on this principle often insinuate them- 

 selves into the very heart of the plant, 

 and do irreparable mischief before they 

 are discovered. But, for the most part, 

 they beset the foliage, and are mostly 

 found on the underside of the leaf, which 

 they prefer, not only on account of its be- 

 ing the most tender, but as it affords them 

 protection from the weather, and various 

 injuries to which they would otherwise 

 be exposed. Sometimes the root is the 



