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sheltered retreats in which to lurk or to get away from the hot dry sum- 
mers and the long cold winters. 
In the third place, the comparative aridity of the region where these 
claims are located renders the growth of them somewhat slower than 
where the precipitation is more bountiful. This slowness of growth, 
while it is an advantage in one respect, aids the insect foes to a con- 
derable extent in their work of destruction. A rank and rapid growth 
places a tree out of danger from external enemies much more quickly 
than will aslow growth. At the same time in rank growth a much 
greater amount of food is furnished for the same number of insects, 
and as a consequence less injury to the tree results than would were 
the growth slower. 
A fourth cause for the rapid increase among these different insects 
in new regions is the absence of such fungoid diseases as are known to 
attack and kill various of these pests. After awhile, however, the 
germs of these diseases become diffused through the soil, vegetable 
débris, and about the encumbering growths, buildings, etc. These 
germs are carried around by the elements and other agencies, and in 
time some of them find lodgment within the bodies of such insects as 
are susceptible to their growth. The result is disease and death. 
Comparative Freedom of different Trees fromthe Attacks of Insect Pests.— 
Up to the present writing I have not sufficiently investigated this por- 
tion of the subject to be entirely positive in my assertions as to the 
kind or kinds of trees most nearly exempt from the attacks of insect 
foes in different regions. None of them are entirely free; but that there 
are trees which suffer less than others in this respect is a well-known 
fact, and can be seen at any time where several kinds are growing side 
by side or in the same grove. Again, a particular kind of tree might 
be troubled in a given locality, while in another it would be compara- 
tively free. Some trees also suffer while small, and others are usually 
injured after they have gained considerable growth and age. These 
variations with regard to insect attacks among different trees, and of 
the same kind at different ages, are governed by laws the explanation 
of which would require much more time and space than I have at my 
command. By looking over the list of insects mentioned above it will 
be seen that no reference is made of any species injuring either the 
Catalpa or Russian Mulberry. The Ash is affected by three, each of 
which at times strips it of foliage while young; the Box Elder by two 
or three; the Willow by a dozen or more; the Cottonwood by four or 
five; the Soft-Maple by several; the Elm a couple; the Honey Locust 
two, ete. 
In treating this subject only such insects have been mentioned as 
have been ascertained to attack the various trees during their first few 
years of growth, and before they have attained any great size. Other 
species of insects injure these trees later on; but, asa rule, these latter 
