BROMLEY: INSECTS AND STORM DAMAGE 
41 
Repeated defoliation results in dying branches and the eventual 
death of the tree. Dying branches, unless there is systematic pruning 
and protection of the cut surfaces with the proper type of wound dress¬ 
ing, means early invasion by wood rots. Too frequently such care is 
wanting. It is significant that about 90 per cent of the shade trees 
severely damaged by the storm had been invaded by wood rots. 
Furthermore, repeated destruction of leaves weakens the tree to the 
extent that a poor root development with consequent inability of the 
tree to resist high winds is the result. It is very probable that repeated 
attacks in earlier years by elm leaf beetle in cities and villages has been 
an important contributing factor in the destruction of so many magnifi¬ 
cent shade trees last September. 
The weakening effects of repeated defoliations by no means end here. 
The next step in the vicious circle is the invasion of cambium borers 
and bark beetles which further contribute to weakening. The menace 
of borers to tree sturdiness is further complicated again by the entrance 
of wood rot producing fungi. 
Among the borers which have produced these conditions in the past 
are the Two-lined Chestnut Borer, a cambium borer of the family of 
flat-headed beetles, which has in southern New England killed thousands 
of weakened oak trees which had been previously defoliated by canker- 
worms or leaf-rollers or weakened by drought, injuries incidental to 
construction of houses or roads, or changes in the water table produced 
by a variety of causes, during the past ten years; the Hickory Bark 
Beetle, which in both New York State and New England has damaged or 
destroyed during the past 20 years thousands of hickories where drought 
or defoliation by canker worms had paved the way for its attack; the 
Bronze Birch Borer, a beetle related to the two-lined chestnut borer, an 
exceedingly lethal pest of ornamental birches as well as native birches 
left exposed in woodlands following cutting or lumbering operations; and 
the Spotted Hemlock Borer, another beetle of the flat-head family, 
which attacks hemlocks weakened by drought or by foliage damage 
resulting from the feeding of such caterpillars as the hemlock span- 
worm. Elm trees have been injured structurally following defoliation 
by invasions of the European elm bark beetle and the leopard moth. 
The Fall Cankerworm and the Pin Oak Leaf-Roller have been partic¬ 
ularly destructive to shade and woodland trees in Connecticut. Re¬ 
peated defoliations by them have killed many trees outright and a much 
larger proportion have been greatly weakened by their attacks. 
