56 On the Aphis Lanigera, or American Blight. 



themselves into the wounded parts of the tree, where the 

 rough edge of the outer bark shelters them from the incle- 

 mency of the weather, as well as from the discerning eye of 

 the gardener ; here they pierce, in security, the inner bark, 

 and make rapid progress in their work of destruction. 

 Whenever an Apple-tree, however, is attacked by these in- 

 sects, their secret operations are soon visible in the cankered 

 appearance of the bark, the sickly aspect, and scarcity of 

 the leaves, and the almost total want of blossom. Upon a 

 closer inspection, their haunts are easily discovered, by the 

 mealy web, in which they are enveloped. This web, when 

 observed through a microscope, resembles an accumulation 

 of the finest cotton threads ; it appears to be produced, not 

 only from the abdomen, but from each division of the bands, 

 which surround their bodies ; intermixed with it are an infinite 

 number of small transparent globules, consisting of a viscid 

 saccharine fluid, the voided excrement of these singular in- 

 sects. In several other species, this excrementitious depo- 

 sition is the cause of the phenomenon, known by the name 

 of Honey Dew ; but in this, the quantity of saccharine 

 fluid produced, is comparatively trifling, or at least, from 

 its local detention in the mealy web, we do not observe it 

 displayed so evidently upon the surface of the surrounding 

 leaves ; sometimes, however, large pieces of the web, inter- 

 mixed with it, fall down, and after a short period, produce 

 a similar effect on the subjacent grass. 



Whether this species derives its origin from a foreign 

 climate, or whether it may be descended from an indigenous 

 stock, having changed its habits by a change of food, I have 

 neither the opportunity, nor the inclination to discuss. It is 



