262 CERASUS VULGARIS. 
Mr. Loudon remarks that, "These holes, by admitting water, accelerate the 
decay of the heart-wood of the tree ; but it is a mistake to suppose, as many do, 
that the decay originates with the wood-pecker, who gets the credit of making 
the holes out of sheer mischief, or for amusement ; the truth being, that decay 
has commenced, and that he is only in search of his food, which consists of the 
larvae which have already begun to eat the wood of the tree." 
Among the insects which infest the common cherry-tree are several species of 
the Geometridas, including the canker-worm, (Phalcenayernata,) and numerous 
wood-eating larva? (Xylophagidse.) The curculio, (Rht/?ichcemis nenuphar,} 
noticed under the head of " Insects, &c," in our article on the domestic culti- 
vated plum, is also known to be the cause of the warty excrescences found on 
the small branches of the cherry, from which circumstance, it was called by 
Professor Peck, RhynchfBnus cerasi, the cherry-weevil. These excrescences, 
which serve as the residence of the larva?, are known to be produced by the 
punctures made in the tree by the beetles ; and, according to Peck, " the sap is 
diverted from its regular course, and is absorbed entirely by the bark, which is 
very much increased in thickness ; the cuticle bursts, the swelling becomes irreg- 
ular, and is formed into black lumps, with a cracked, uneven, granulated sur- 
face. The wood, besides being deprived of its nutriment, is very much com- 
pressed, and the branch above the tumour perishes." The same remedies wil 
apply in the present case as those recommended for the excrescences found on 
the domestic cultivated plum-tree. 
But by far the most pernicious enemy to the common cherry-tree, is the slug- 
fly, Blennocampa ce?'asi, of Harris. He describes the perfect insect, in his 
' ; Report," as being "of a glossy Mack colour, except the two first pairs of legs, 
which are dirty yellow or clay-coloured, with blackish thighs, and the hind-legs, 
which are dull black, with clay-coloured knees. The wings are somewhat con- 
vex, and rumpled or uneven on the upper side, like the wings of the saw-flies 
generally. They are transparent, reflecting the changeable colours of the rain- 
bow, and have a smoky tinge, forming a cloud, or broad band across the middle 
of the first pair; the veins are brownish. The body of the female measures 
nither more than one fifth of an inch in length; that of the male is smaller. In 
the year 1828, I observed these saw-flies, on cherry and plum-trees, on the 10th 
of May; but they usually appear towards the end of May or early in June. 
Soon afterwards some of them begin to lay their eggs, and all of them finish this 
business and disappear, within the space of three weeks. Their eggs are placed, 
singly, within little semicircular incisions through the skin of the leaf, and gene- 
rally on the lower side of it. ***** On the fourteenth day afterwards, 
the eggs begin to hatch, and the young slug-worms continue to come forth from 
the 5th of June to the 20th of July, according as the flies have appeared early or 
late in the spring. At first, the slugs are white; but a slimy matter soon oozes 
nut of their skin and covers their backs with an olive-coloured, sticky coat. 
They have twenty very short legs, or a pair under each segment of the body, 
except the fourth and the last. The largest slugs are about nine- twentieths of 
an inch in length, when fully grown. The head, of a dark-chesnut colour, is 
small, and is entirely concealed under the fore-part of the body. They are larg- 
est before, and taper behind, and in form somewhat resemble minute tadpoles. 
They have the faculty of swelling out the fore part of the body, and generally 
rest with the tail a little turned up. These disgusting slugs live mostly on the 
upper sides of the leaves of the pear and cherry-trees, and eat away the substance 
thereof, leaving only the veins and the skin beneath, untouched. Sometimes 
twenty or thirty of them may be seen on a single leaf; and, in the year 1797, 
they were so abundant in some parts of Massachusetts, that small trees were 
covered with them, and the foliage entirely destroyed; and even the air, by 
