44 
WAYSIDE AND WOODLAND TREES. 
Both species are subject to a great amount of variation, and 
in nurserymen’s catalogues these forfns have appropriate 
names, but they are not regarded as of sufficient permanence 
to merit scientific distinction. In point of age — Elms are 
known to exceed five hundred years. 
Common Elm. 
Among the insects that feed upon the Elm’s foliage, the 
most noteworthy is the caterpillar of the fine Large Tortoise- 
shell Butterfly ( Vanessa polychloros'). I have already mentioned 
the relationship subsisting between Elms and Nettles, and it 
is a point worth noting that nearly all our native species of 
Vanessa feed in the larval state upon the leaves of the Nettle. 
In London parks and squares the Elms are much infested 
