VI.] DISEASES OF FRUIT-TREES. 221 



Stripped of every leaf by the caterpillars. Of their progenitors I 

 know little ; but that they appear in the winter, when the leaf 

 has fallen, as a little crusty shell-like ring fastened tightly round 

 the twigs of the tree, and generally upon apple-trees. This o ust 

 is not more than half an inch long, and it is pricked all over in 

 regular rows of holes, looking something like a piece of an 

 old thimble twisted round the twig. In the spring a swarm of 

 little caterpillars issues from this crust, and works its way all over 

 the tree ; and, to an ordinary observer, they make their first ap- 

 pearance in a web formed into the shape of a bag or sort of wal- 

 let attached to the branches of trees. And this bag is a small 

 thing at first ; but it grows larger and larger as the caterpillars 

 within it increase in size. If you open one of these bags, a goodly 

 tribe glads your sight ; and, if you leave the bag till the cater- 

 pillars grow too big for it and open it themselves, they sally forth 

 in every direction, and strip the tree of its leaves. Prevention is 

 not, however, in this case, very difficult. If they come on espa- 

 liers, you pick the bag off as soon as you perceive it, and crush it 

 under your foot. If they come on standard-trees, you must take 

 a ladder ; but a better way is to load a gun with powder, and to 

 blow the bags from the trees. If once they escape from the bag 

 and go on their travels, you have no remedy. If you shake the 

 tree and bring part of them to the ground, they crawl up again. 

 Lime has no effect upon them ; and your only hope is that your 

 other enemies, the sparrows, will lend their assistance in deliver- 

 ing you from these ; and I do verily believe that, were it not for 

 the sparrows, and other birds, these insects would make it next to 

 impossible to cultivate gardens in England. They have no slugs 

 and snails in America ; but caterpillars they have, and they some- 

 times strip an orchard of every one of its leaves. There are cater- 

 pillars which infest the cabbages and the Swedish turnip, and 

 some other herbaceous plants. These manifestly proceed from 

 the butterfly ; but, unfortunately, they do not make their appear- 

 ance in little pockets or bags ; but you make the first discovery 

 of the honour of the visit that they are paying you by perceiviiig 

 their gnawings upon the edgings of the leaves of the plants. Let 

 them alone for a little while, and they will go from cabbage to 

 cabbage until there is not a bit of leaf left in the whole patch. 

 They leave you the skeleton of a cabbage, taking away all the 

 flesh, and leaving all the bones; that is to say, the stalk of the 



