CHAP. XLII. ROSACEJE. Py'rUS. 907 



explains the reason of their sudden appearance : it shows how one day not a 

 single caterpillar may be visible on the trees, and the next they may be 

 swarming with larvse of so large a size as to rebut the idea of their having 

 been recently hatched. Besides, their latter habit of feeding on the leaves 

 externally is so little like their former one of feeding on them internally, that 

 any one who had not satisfied himself, by examination, that both habits are 

 proper to the same cater[)illars, would scarcely suppose this to be the case. 

 AVhile the caterpillars are within the leaves, they are of a yellowish colour, 

 though they become darker at each change of skin. It is in this state that I 

 would recommend their destruction, by gathering and burning every leaf 

 which by its ontward appearance betrays tiie internal ravages. Their nests 

 are so difficult to discover, that searching for them seems entirely out of the 

 question ; and I am much afraid that, could any wash be conveniently ap- 

 plied to the small twigs, whatever might be sufficiently powerful to penetrate 

 the glutinous covering would at the same time injure the tree. 



'"Having satiated themselves with the growing hopes of the gardener, who 

 endeavours, but in vain, to stop their destructive career, they prepare for the 

 pupa state by spinning white cocoons of an ellipsoidal form. In a short 

 time they emerge from their pupas, and may be seen in the evening, but more 

 particularly in the early morning, flying by hundreds round those devoted 

 trees which are, in the following 3ear, to be the scene of similar ravages, 

 unless circumstances for which we cannot account should prevent their mul- 

 tiplication." 



The LarvcB of various Moths feed on the leaves, and some even penetrate 

 into the young shoots, of apple trees. One caterpillar, often found rolled up 

 in an apple tree leaf, is of a chestnut-brown colour, with a black head ; and 

 another is green, with a few black hairs scattered over its body. The eggs of 

 some of these moths are deposited in the preceding autumn, upon the 

 branches, where they are fixed so firmly and are so little susceptible of injury 

 from variation in temperature, that it is difficult to prescribe any application 

 that would prevent caterpillars being hatched from them in the following 

 spring. 



There is also a moth which lays its eggs in the buds, the caterpillar of which 

 eats its way through the bud into the soft wood, in the case of flower buds ; 

 and into the herbaceous slioot of the current year, in the case of leaf buds ; 

 occasioning the shoots and spurs soon afterwards to die. We are not aware 

 thatthe economy of this insect has been studied and recorded, though it 

 appears to belong to the family of Mgevicv. These, according to Newman, 

 " are produced from almost colourless maggots, which have the penultimate 

 segment diminished, and without any horn ; which have six corneous and 

 pointed, and ten wart-like, and almost useless, feet ; which feed in the interior 

 of the trunks of trees, throughout the winter and spring ; and then, spinning 

 a cocoon among their food, change into remarkably rough and vivacious 

 pupae, which in ten or twelve days produce perfect insects." {Entom. Mag., 

 vol. i. p. 71.) See Encyc. ofGarcL, edit. 1835. art, Apple. 



Tlie common Cockchafer (il/elolontha vulgaris Fab.), in its perfect state, 

 attacks the leaves of all trees; and, though it has been found chiefly devour- 

 ing those of the oak, (in treating of which tree the insect will be figured and 

 described), yet it is also very injurious to those of the apple. Smoking them 

 off, or shaking the branches of the tree till they drop to the ground, and then 

 picking them up and destroying them, are the only means of alleviating the 

 injuries done by insects already in their winged state; and they have the 

 further advantage, with reference to the future, that they prevent the insects 

 from laying their eggs. (See the article Quercus.) 



Anomala (Scarabcc^us) horticola, a beetle called, in Norfolk, the chov}', is 

 there deemed very injurious to apple trees, and to other trees and plants, as 

 it feeds both on the leaves and flowers. 



The JEcidium cancelldtum (the fungus mentioned as growing on the leaves 

 of the pear tree, and producing what is called mildew) is also not unfrequent 



