414 INSECTS INJURIOUS TO VEGETATION. 



devour, and thus proceed, from leaf to leaf, down the branch, 

 till they have grown to their full size. They then average five 

 eighths of an inch in length, are somewhat slender and taper- 

 ing behind, and thickest before the middle. They have twenty- 

 two legs. The head and the tip of the tail are black ; the 

 body, above, is light green, paler before and behind, with two 

 transverse rows of minute black points across each ring ; and 

 the lower side of the body is yellowish. After their last 

 moulting they become almost entirely yellow, and then leave 

 the vine, burrow in the grovind, and form for themselves small 

 oval cells of earth, which they line with a slight silken film. 

 In about a fortnight after going into the ground, having in the 

 mean time passed through the chrysalis state, they come out 

 of their earthen cells, take wing, pair, and lay their eggs for a 

 second brood. The young of the second brood are not trans- 

 formed to flies until the following spring, but remain at rest 

 in their cocoons in the ground through the winter. For some 

 years previous to the publication of my " Discourse," I ob- 

 served that these insects annually increased in number, and, 

 in the year 1832, they had become so numerous and destruct- 

 ive that many vines were entirely stripped of their leaves by 

 them. Whether the remedies then proposed by me, or any 

 other means, have tended to diminish their numbers, or to 

 keep them in check, I have not been able to ascertain, and 

 have had no further opportunity for making observations on 

 the insects themselves. At that time, air-slacked lime, which 

 was found to be fatal to these false caterpillars of the vine, 

 was advised to be dusted upon them, and strewed also upon 

 the ground under the vines, to insure the destruction of such 

 of the insects as might fall. A solution of one pound of com- 

 mon hard soap in five or six gallons of soft water, is used by 

 English gardeners to destroy the young of the gooseberry saw- 

 fly ; and the same was recommended to be tried upon the in- 

 sects under consideration. 



All the young of the saw-flies do not so closely resemble 

 caterpillars as the preceding; some of them, as has already 

 been stated, have the form of slugs or naked snails. Of this 

 description is the kind called the slug-worm in this country. 



