Queries and Answers. 525 



matter of the leaf. Brown and lifeless circular spots in consequence appear 

 upon the leaves, such as an excess of heat would occasion ; and I have known 

 several gardeners who have supposed it to be caused by solar action. These 

 lifeless spots enclose the larvae of the moth above mentioned, which do not 

 exceed a line in length. Whenever the leaves of a pear tree contain many of 

 these, the fruit does not acquire nearly its natural size, and it ripens without 

 acquiring either sweetness or flavour. This insect is an old inhabitant of our 

 gardens : 1 first observed it half a century ago, but it appears latterly to have 

 become much more abundant. It greatly prefers some varieties of pears to 

 others ; the Chaumontelle appears, amongst the varieties in my garden, its 

 favourite, and the glout morceau that which it likes least. The moth is, I 

 believe, but little known ; for Mr. Curtis, who was so kind as to give me the 

 name of it, did not possess a specimen till he received one from me. My pear 

 trees had sustained, during many successive years, so much injury from the 

 depredation of this insect, and their fruit had in consequence become so de- 

 fective in freshness and flavour, that I resolved to uproot the whole of them, 

 if I failed to succeed in destroying or driving away the insects ; but in the last 

 summer I had the good fortune to obtain perfect success in driving them away 

 by the means which I proceed to describe. 



" Early in the spring of the year, when the blossom buds of my pear trees 

 were about the size of large peas, water, which held in suspension a mixture 

 of lime and flower of sulphur and soot, in about equal portions, was thrown 

 by an engine over the pears trees and the surface of the wall to which they 

 .were trained. I applied this mixture because I had observed, as I have stated 

 in a former communication, that it had apparently prevented the appearance 

 of blistered leaves upon my peach and nectarine trees, though by what mode 

 of operation 1 was then, as I still am, wholly at a loss to conjecture; but 

 since the first application of it, 1 have not seen a single blistered leaf upon 

 any tree to which it was applied. I, of course, distinguish blistered leaves 

 from such as have been made to contract by the bite of the aphis. 



" The moths appeared as abundant as in the preceding year ; and I then 

 caused my trees to be washed once in every week during a month, after I 

 witnessed the first appearance of the moth, with a weak infusion of tobacco in 

 water : this mode of treatment proved successful, and the foliage of my pear 

 trees, and some plum trees contiguous, escaped all injury. The moths were, 

 however, only driven away ; for the leaves of two pear trees which grew at 

 some distance were almost wholly destroyed, and the foliage of the medlar and 

 cherry trees in the vicinity sustained a good deal of injury from them. Nearly 

 all the leaves which contained any of the larvse were collected and burned, 

 and comparatively very few of the larvse escaped ; and I do not at all doubt 

 but that, by adopting the same measures next year, I shall succeed in securing 

 my pears from future injury, 



" There is another species of insect which frequently injures the pear tree, 

 whose depredations are less visible, and consequently less known to gardeners. 

 It has greatly the appearance of an aphis, and is found dispersed over the 

 under surface of the leaves whilst young, and is always immersed in a globule 

 of honey. In their more mature state, these insects are found congregated 

 round the base of the L;ids, particularly those which are calculated to form 

 blossom buds. In this, as in their first situation, they emit much honey, and 

 the transmutation of the leaf bud into a blossom bud is prevented. A large 

 number of humble bees and wasps are always attracted by the honey ejected 

 by this insect, which will never fail to indicate its presence to the gardener. 

 It is in size a little less than the black aphis usually seen upon the cherry tree; 

 and its colour, when it is young, is a dull green, with dotted lines of pale 

 brown ; and in its mature state its colour is dark brown, with transverse 

 stripes of green across its back. The colour of the male, which is winged, is 

 nearly black, except the upper part of the abdomen, which is a dull flame- 

 colour. It is (as Mr. Curtis informs me), the Psylla Pyri of Linnaeus. I 

 noticed it in the garden here about forty years ago, when it rendered all the 



