138 RE'pORT/oi 1 S^kfi^COMMISSTONER OF AGRICULTURE. 



anotlier "rftbfe bf'constriictiofr'the foregoing nozzles are made to dis- 

 charge the atomized spray in the direction of the main axis of the blast- 

 pipe, which is sometimes desirable, as in applying the poison to trees 

 or in directing it horizontally or downwards. For these purposes the 

 extension -tube may be removed entirely from its juncture, r, and with 

 such a short discharge-pipe spray may be thrown immediately there- 

 from without reatomizing, yet a much finer quality of mist is produced 

 by adding one of the reatomizing nozzles thereto. Again, the machine 

 can be used by substituting a person's breathing apparatus for the 

 bellows. In this case, as in Plate IY, Fig. 8, a blow-pipe and mouth- 

 piece, o, should be added, that the mouth may be far from the poison. 

 This is the cheaper form and may be employed by careful persons. The 

 other parts of Fig. 8 are the same as already explained. 



Finally, for similar purposes a small squirting apparatus, pictured in 

 Plate V, Figs. 1-5, may be described. It consists of a small telescope- 

 pump having the internal structure of the stirrer-pump elsewhere de- 

 scribed. The cylinder, c, is held by one hand, and the hollow piston-rod, 

 x, by the other. The piston may be held steady while the cylinder is 

 reciprocated back and forth upon it. Being a double-acting pump, a 

 constant pressure and stream is applied. It draws the fluid from a 

 knapsack reservoir, fc, or other receptacle, through the suction-hose, fe, 

 which is joined to the pump cylinder at c. The valve, which occurred 

 in the base of the pump already described, is here inserted in the suc- 

 tion-hose, and by means of the hose is held in connection with the 

 pump. Also in this case the fluid is ejected from the tubular piston- 

 rod through its extension-pipe, a?, u, and the nozzle, s, which is the same 

 as those already referred to. The extension-pipe may be forked, as in 

 Figs. 4 and 5, to apply two or more jets of spray, or it may be entirely 

 removed when desired. Also the pump is well adapted for extinguish- 

 ing fires or squirting into trees, &c., while it will supply itself by suction 

 from a bucket or any other suitable source. 



REPORT ON THE CAUSES OF DESTRUCTION OF EVER- 

 GREEN FORESTS IN NORTHERN NEW ENGLAND AND 

 NEW YORK. 



BY A. S. PACKARD, JR., Special agent o/ the Division. 

 THE LAECH SAW-FLY WOEM. 



(Nematus erichsonii Hartig.) 



Order HYMENOPTERA ; family TENTHREDINIDJE. 



[Plate III, Fig. 1, and Plate XIII, Figs. 1, la, 2, 3, 4.] 



HISTORY OF ITS RAVAGES. 



In Bulletin 7 of the United States Entomological Commission we 

 enumerated all the insects known to affect or in any way to prey upon 

 the larch or hackmatack. There were none then known to abound upon 

 or to seriously injure this tree, which has heretofore been supposed to be 

 as free as even the hemlock from insect pests. The hackmatack, as is 

 well known, is one of the most important lumber trees in Maine, as it 



