APHIS. 



object of their choice, which, from the na- 



tureof thcs i'.c would n.t, a 



pri ori, expect ; yet 1 havr seen t IK- roots 



! with them, and 



the v hole crop rendered sickly and of lit- 

 tie \alue; but such instances arc ran-. 

 They seldom attach themst Ivcs to the 

 hark of trees, like the aphis salicis, which, 

 bcingone of our largest species, and hence 

 ng superior (trength,u enabled to 

 penetrate a substance harder than the 

 leaves themselves. In the quality of the 

 excrement voided by these insects, there 

 is something wonderfully extraordinary. 

 \Vrre a person accidentally to take up a 

 book, in which it was gravel}- asserted, 

 that in some countries there were certain 

 animals which voided* liquid sugar, he 

 would lay it down, regarding it as a fabu- 

 lous tale, calculated to impose on the cre- 

 dulity of the ignorant ; and yet such is 

 literally the truth. Mr. Curtis collected 

 some on a piece of writing-paper, from a 

 brood of the aphis salicis, and found it to 

 be sweet as sugar ; and observes, that, 

 were it not for the wasps, ants, flies, and 

 other insects, that devour it as quickly as 

 it is produced, it might, no doubt, be col- 

 lected in considerable quantities, and by 

 the processes used with other saccharine 

 juices, might be converted into the choic- 

 est sugar or sugar-candy. Tin- sweetness 

 of tins cxcrcnu ntitious substance, the 

 giossv appearance it gave the leaves it fell 

 upon, and the swarm of insects this matter 

 attract.-,, led him to imagine that the ho. 

 ney-dew of plants was no other than this 

 secretion, which further observation has 

 since fully confirmed ; and no^, as its name 

 implies, a sweet substance falling from the 

 atmosphere. On this opinion it is further 

 remarked, thai it neither fails from the 

 atmosphere, nor issues from the plant it- 

 I is easily demonstrated. If it fell 



from theatn would cover every 



tiling it fell upon indiscriminately, whcre- 

 .levertind it but on certain living 

 plants and trees. \Ve iiiui it also on plants 

 in stoves and green-hoi. . d with 



glass. If it exuded from the })!:tn;, it would 

 appear on all the leaves generally and u- 

 nifonnly ; when 



treineh irregular, not alike on any two 

 .\e tree or plant, some 

 having none of it, and others feing cover- 

 ed \\ ith it but partially. It is probable 

 that ill \ists ;m\ hoiiev -dew but 



whevi aphides : though such 



often pass unnoticed, being hidden on the 

 underside of the leaf: and wherever ho- 

 ney-dew is observable upon a leaf, aphides 

 will be found on the undi r side of the leaf 

 or leaves immediately above it, and under 



no other circumstance whatever. If by ac- 

 ckleot Anything should intefvi n. !>. 

 the aphides and the leaf next hem nth 

 Uiem, i here well he nohonev-dew on that 

 leaf: and thus he conceives It is incontro- 

 vertibly proved, that iphides are the trur 

 and only source of honey-dew. Of the 

 British species of aphides, one of the larg- 

 est and most remarkable is the aphis sali- 

 cis, \\ Inch is found on the different kinds of 

 wil;ri\\ s. When bruised, these insects stain 

 the fingers with red. Towards the end of 

 September multitudes of the full-grown 

 insects of this species, both with and with - 

 out wings, desert the willows on which 

 they feed, and ramble over every neigh- 

 bouring object in such numbers,*that we 

 can handle nothing in their vicinity with- 

 out crushing some of them, while those in 

 a younger or less advanced state still re- 

 main in large masses upon the trees. Aphis 

 rosx is very frequent, during the summer 

 months, on the young shoots and buds of 

 roses : it is of a bright green colour : the 

 males are furnished with large transpa- 

 rent wings. A. vitis is most destructive 

 to vines; as A. ulmi is to the elm-tree. 

 Plate I. Entomology, fig. 3. 



It is found, that where the saccharine 

 substance has dropped from aphides for 

 a length of time, as from the aphis salicis 

 in particular, it gives to the surface of the 

 bark, foliage, &c. that sooty kind of ap- 

 pearance, which arises from the explosion 

 of gunpowder : it looks like, and is some- 

 times taken for, a kind of black mildew 

 In most seasons the natural enemies of the 

 aphides are sufficient to keep them in 

 check, and to prevent them from doing 

 essential injury to plants in the open air . 

 but there are times, once perhaps in four, 

 five, or six years, in which they are mul- 

 tiplied to such an excess, that th 

 mesms of diminution fail in preventing 

 them from doing irreparable injury to 

 certain crops. 



To prevent the calamities which would 

 infallibly result from an accumulated 

 multiplication of the more prolific animals. 

 it has been ordained by the Author of 

 nature, that such should be diminished 

 in KTVing M t'-oil for others. On this 

 principle, most animals of this kind ha\v 

 one or more natural enemies. The lulp- 

 :iis, which is the scourjre <,f the 

 , >le kingdom, has to contend with 

 many: of these, the principal are, tho> 

 coccinella, the ichneumon aphidum, and 

 the musca aphidcvora. The gr< :/ 

 s'nnerof the aphides is the coccinella, 

 or common lady-bird. During the winter 

 this insect secures itself under the bark of 



