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. ‘T‘he most per- 
nicious, if not the most universal of these, are the canker-worms, 
(Anisopteryx vernata and pometaria) 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 Cimber 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; Cib., p. 283,) the caterpillars of 
the Antiopa butterfly, (ab., p. 219,) of the Semicolon butterfly, 
Vanessa interrogationis ; (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. Tse American Eim. Wuite Exm. 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 ina 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 
