210 INDIRECT INJURIES CAUSED BY INSECTS. 



causing them to wither either partially or totally. 

 You have doubtless observed what is called the honey- 

 dew upon the maple and other trees, concerning which 

 the learned Roman naturalist Pliny gravely hesitates 

 whether he shall call it the sweat of the heavens, the 

 saliva of the stars, or a liquid produced by the purga- 

 tion of the air* ! ! Perhaps you may not be aware that 

 it is a secretion of Aphides, whose excrement has the 

 privilege of emulating sugar and honey in sweetness 

 and purity. It however often tarnishes the lustre of 

 those trees in which these insects are numerous, and is 

 the lure that attracts the swarms of ants which you 

 may often see travelling up and down the trunk of the 

 oak and other trees. The larch in particular is inha- 

 bited by an Aphis transpiring a waxy substance like 

 filaments of cotton : this is sometimes so infinitely mul- 

 tiplied upon it as to whiten the whole tree, w hich often 

 perishes in consequence of its attack. The beech is 

 infested by a similar one. Some animals also of this 

 genus inhabiting the poplar, elm, lime, and willow, re- 

 side in galls they have produced, that disfigure the 

 leaves or their footstalks. Perhaps those resembling 

 fruit, or flowers, or moss, produced by the Aphis of the 

 fir {Aphis Abietis, L.), the different species of gall-gnats 

 (CecidoniT/ioy Latr.), or occasioned by the puncture and 

 oviposition of the various kinds of gall-fiies {Cj/nips, 

 L.), may be regarded rather as an ornament than as 

 an injury to a tree or shrub ; yet when too numerous 

 they must deprive it of its proper nutriment, and so oc- 

 casion some defect. And probably the enormous wens, 

 and other monstrosities and deformities observable in 



* Hist. Nat. 1. xi. c. 12. 



