THE LARCH WORM. 879 



23. Semiothisa hisignata (Walk.) Observed Aug. 4, Brunswick, Me. 



24. Aplodes coniferaria Pack. 



25. Cleora sp. 



26. 10-lined pine-span worm, No. 82, Bulletin No. 7. 



INSECTS INJURIOUS TO THE LARCH OR TAMARACK. 



Larix americana. 

 AFFECTING THE LEAVES. 



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 

 sends down a single large root, which grows laterally, forming a bend 

 at right-angles to the trunk, so that it is used for " knees" in building 

 vessels, the smaller trees being used for the same purpose in boat-build- 

 ing. It is also used for railroad ties. 



The larch grows in wet swamps, or standing water, where the spruce 

 or hemlock as well as pines would not flourish, hence its growth en- 

 hances the value of extensive swampy tracts in Maine, where the water 

 often stands all summer, even through the severest droughts. 



1. The larch saw-fly worm. 

 Nematus erichsonii Haitig. 

 Order Htmexoptera ; family Tenthredinid^. 

 (Plate IX, Fig. 1, la, 16, Ic, Id, and Plate xxvi, Figs. 1, la, 2, 3, 4, 6.) 



Its devastations in Maine. — Our attention was first called to this in- 

 sect late in August, 1882, and we first saw the effects of its ravages at 

 Brunswick, Me., where it had partly or entirely stripped the hackma- 

 tacks in a very wet swamp on the banks of the Androscoggin Eiver, on 

 the farm of Hon. C. J. Oilman, who called our attention to the ravages 

 which had been committed earlier in the season. On examining the 

 growth in company with him, we found that most of the trees, both 

 large ones, 6 to 10 inches in diameter„and small saplings, 6 to 15 feet 

 in height, had been attacked ; some of the trees were stripped, others 

 partially so, while others had wholly escaped. The trees in the middle 

 of the swamp appeared to have suffered most, while the smaller ones 

 on the edge or on higher land were less injured. 



By jarring the trees a few young, half-grown worms of the second 

 brood which had not yet undergone their last molt, and a single fully- 

 grown larva were collected, while the cocoons from which the saw-flies 



