420 INSECTS INJURIOUS TO ^TEGETATION. 



the slugs are white ; but a slimy matter soon oozes out of 

 their skin and covers their backs with an olive-colored 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 chestnut color, is 

 small, and is entirely concealed under the fore part of the 

 body. They are largest 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 side 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 en- 

 tirely destroyed; and even the air, by passing through the 

 trees, became charged with a very disagreeable and sickening 

 odor, given out by these slimy creatures. The trees attacked 

 by them are forced to throw out new leaves, during the heat 

 of the summer, at the ends of the twigs and branches that 

 still remain alive ; and this unseasonable foliage, which should 

 not have appeared till the next spring, exhausts the vigor of 

 the trees, and cuts off the prospect of fruit. The slug-worms 

 come to their growth in twenty-six days, during which period 

 they cast their skins five times. Frequently, as soon as the 

 skin is shed, they are seen feeding upon it ; but they never 

 touch the last coat, which remains stretched out upon the leaf. 

 After this is cast off, they no longer retain their slimy appear- 

 ance and olive color, but have a clean yellow skin, entirely 

 free from viscidity. They change also in form, and become 

 proportionally longer ; and their head and the marks between 

 the rings are plainly to be seen. In a few hours after this 

 change, they leave the trees, and, having crept or fallen to the 

 ground, they burrow to the depth of from one inch to three or 

 four inches, according to the nature of the soil. By moving 

 their body, the earth around them becomes pressed equally on 



