286 WOODY PLANTS OF MASSACHUSETTS. 



are here preferred, as the wood has the disadvantage of being 

 liable to warp and shrink, unless very long and thoroughly sea- 

 soned, or kept moist. Both living and dead, it is liable to the 

 attacks of insects and worms, which strip it of its foliage, pen- 

 etrate into its bark and wood, and lessen the value of its timber. 



A great many insects feed upon its leaves. The most per- 

 nicious, if not the most universal of these, are the canker-worms, 

 (Anisopteryx vernata and pometarid) one or two species of 

 which, with their habits, times and mode of destruction, have 

 been carefully described by Dr. Harris, (Report, p. 334 — 341.) 

 Less injurious are the span-worms, called, when arrived at their 

 perfect moth state, Hybernia tiliaria, the Lime-tree winter- 

 moth, (ib., pp. 341, 342.) The Cimbex ulmi a species of saw- 

 fly, (ib., pp. 374, 375,) feeds on the leaves of the elm, during 

 its caterpillar existence, and the caterpillars of some of the most 

 beautiful of the moths and butterflies, such as the stinging cat- 

 erpillars of the Saturnia moth ; (ib., p. 283,) the caterpillars of 

 the Antiopa butterfly, (ib., p. 219,) of the Semicolon butterfly, 

 Vanessa inter rogationis ; (ib., p. 220,) of the Progne butterfly, 

 Vanessa progne, (ib., p. 222,) and the enormous caterpillars of 

 the Ceratomia quadricornis, which are sometimes three inches 

 and a half long, (ib., p. 227), are all found on this tree, and do 

 more or less harm by devouring its leaves. 



There are two species of elm common in Massachusetts, the 

 American, and the Slippery Elm ; another is sometimes found 

 indigenous ; and two varieties of the European Elm have been 

 introduced. 



Sp. 1. The American Elm. White Elm. Ulmus Ameri- 

 cana. L. 



The American elm is, in most parts of the State, the most 

 magnificent tree to be seen. From a root, which, in old trees, 

 spreads much, above the surface of the ground, the trunk rises 

 to a considerable height in a single stem. Here it usually di- 

 vides into two or three principal branches, which go off by 

 a gradual and easy curve. These stretch upwards and out- 

 wards with an airy sweep, — become horizontal, the extreme 



