INDIRECT INJURIES CAUSED BY INSECTS. 153 



of the metropolis in 1782, when rewards were offered for collecting the 

 caterpillars, and the churchwardens and overseers of the parishes attended 

 to see them burnt by bushels. You may have observed perhaps in some 

 cabinets of foreign insects an ant, the head of which is very large in pro- 

 portion to the size of its body, with a piece of leaf in its mouth many 

 times bigger than itself. These ants, called in Tobago parasol ants (Atta 

 cephalotes), cut circular pieces out of the leaves of various trees and 

 plants, which they carry in their jaws to their nests, and they will strip a 

 tree of its leaves in a night, a circumstance which has been confirmed to 

 me by Captain Hancock.^ Stedman mentions another very large ant, 

 being at least an inch in length, which has the same instinct. It was a 

 pleasant spectacle, he observes, to behold this army of ants marching con- 

 stantly in the same direction, and each individual with its bit of green leaf 

 in its mouth.^ The insects injurious to deciduous trees mostly leave the 

 fir and pine tribes untouched ; but these, on the other hand, are subject to 

 have their foliage ravaged by a great variety of insect enemies peculiar to 

 themselves, to some extent in this country, but far more on the Continent, 

 as by the larvs of various moths (Dendrolimis pini, Psilura monacha, 

 Achatia piniperda, Bupalus piniarius, Orthotcenia turionana and resinella, 

 &c.) ; and of not fewer than three species of saw-fly {Lophyrus pini and 

 rufus and Pamphilius erythrocephala).^ The injury thus caused to trees 

 by insects is not confined to the mere loss of their leaves for one season ; 

 for it occasions them to draw upon the funds of another, by sending forth 

 premature shoots and making gems unfold, that, in the ordinary course, 

 would not have put forth their foliage till the following year. 



Other insects, though they do not entirely devour the leaves of trees 

 and plants, yet considerably diminish their beauty. Thus, for instance, 

 sometimes the subcutaneous larvae undermine them, when the leaf exhibits 

 the whole course of their labyrinth in a pallid, tortuous, gradually dilating 

 line — at others, the Tortrices disfigure them by rolling them up, or the 

 leaf-cutter bees by taking a piece out of them, or certain Tinea, again by 

 eating their under surface, and so 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 nat- 

 uralist Pliny gravely hesitates whether he shall call it the sweat of the 

 heavens, the saliva of the stars, or a liquid produced by the purgation of 

 the air ! \^ Perhaps you may not be aware that it is a secretion of Aphi- 

 des, 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 traveling up and down the trunk 

 of the oak and other trees.^ The larch in particular is inhabited by an 



' The same intelligent gentleman related to me, that a person having taken some land 

 at Bahia in the Brazils, he was compelled by these ants, which were so numerous as to 

 render every effort to destroy them ineffectual, to relinquish the occupation of it. Their 

 nests were excavated to the astonishing depth of fourteen feet. Merian, Insect. Sur. 18. 

 Smeathraan on Termites, Phil. Trans. Ixxi. 39. note 35. 



* Stedman, ii. 142. 3 Kollar, on Ins. inj. to Gardeners, &c. 323 — 356. 



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



* It is contended by some observers, that besides the honey-dew caused by Aphides, there 

 is another arising solely from a morbid exudation of the saccharine juices of trees. This 

 is certainly possible ; but I may observe, that in the course of more than thirty years which 



