146 INDIRECT INJURIES CAUSED BY INSECTS. 



He often found in young pears, on opening them, a larva of this genus.^ 

 A little moth likewise is mentioned by Mr. Forsyth *as very injurious to 

 this tree.^ 



But of all our fruits none is so useful and important as the apple, 

 and none sulFers more from insects, which according to jMr. Knight are a 

 more frequent cause of the crops failing than frost. Here, as in the pear- 

 trees, the bark, and consequently the whole tree, suffers from the larvae of 

 Carpocapsa Wcsberana, and of Tinea corticella L., as well as of a Scoly- 

 tus nearly related to S. destructor, but perhaps distinct, which I found 

 infesting it in Guernsey in 1836; and in Austria the larva of another 

 beetle (Trypodendron dispar) pierces into the heart of young healthy 

 trees, and destroyed (jSI. Schmidberger) several of his stock.^ The sap 

 is often injuriously drawn off by Psylla mali* ; and by a minute Coccus, 

 of which the female has the exact shape of a muscle shell (C. arborum 

 linearis GeofFr.), and which Reaumur has accurately described and figur- 

 ed.^ This species so abounded in 1816 on an apple tree in my garden, 

 that the whole bark was covered with it in every part ; and I have since 

 been informed by Joshua Haworth, jun. Esq., of Hull, that it equally 

 infests other trees in the neighborhood. Even the fruit of a golden pippin 

 which he sent me were thickly beset with it. But the insect which most 

 injures our apple trees by drawing oft' their sap, and which has been known 

 in this country only since the year 1787, is the apple-aphis, called by 

 some the Coccus, and by others the American blight. This is a minute 

 insect, covered with a long cotton-like wool transpiring from the pores of 

 its body, which takes its station in the chinks and rugosities of the bark, 

 where it increases abundantly, and, by constantly extracting the sap, 

 causes ultimately the destruction of the tree. Whence this pest was first 

 introduced is not certainly known. Sir Joseph Banks traced its origin to 

 a nursery in Sloane Street ; and at first he was led to conclude that it had 

 i)een imported with some appletrees from France. On writing, however, 

 to gardeners in that country, he found it to be wholly unknown there. It 

 was therefore, if not a native insect, most probably derived from North 

 America, from whence apple trees had also been imported by the proprie- 

 tor of that nursery. Whatever its origin, it spread rapidly. At first it 

 was confined to the vicinity of the metropolis, where it destroyed thou- 

 sands of trees. But it has since found its way into other pans of the 

 kingdom, particularly into the cider counties ; and in 1810 so many per- 

 islied from it in Gloucestershire, that, if some mode of destroying it were 

 not discovered, it was feared the making of cider must be abandoned. 

 Sir Joseph Banks long ago extirpated it from his own apple trees, by the 

 simple method of taking oft" all the rugged and dead old bark, and then 

 scrubbing the trunk and branches with a hard brush.^ 



» Reaum. ubi supr. 475. - On Fruit Trees, 271. 



■' Kiillar, on Ins. inj. to Gardeners, tec. 25ri. ■» Ibid. 278. ' Reaum. iv. 69. t. 5. f. 6, 7, 

 " This Apliis is evidently the insect described in Illiger's Magazin, i. 450. under the name 

 of A. laniaera, as having done great injury to the apple-trees in the neighborhood of Bre- 

 men in 180 1. That it is an Aphis and no Coccus is clear from its oral rostrum and the wings of 

 the male, of which Sir Joseph Banks had an admirable drawing by Mr. Bauer. On this 

 Aphis see Forsyth, 2r)5. ; Monthly Mag. x,\xii. 320. ; and also for August, ISll. ; and Sir 

 Joseph Banks in the Horticultural Socicli/s Transactions, ii. Ili2. Those Aphides that tran- 

 spire a cottony excretion are now considered, as before stated, as belonging to a distinct 

 genus, under the name of Lachnus, Illig. ; Myzoxyle, Blot j Eriosoma, Leach. 



