INSECT ENEMIES OF WESTERN FORESTS Si 
small, drab-colored moths. During heavy infestations practically all 
of the leaves on the lower portions of the trees are attacked, but 
infestation seldom extends above 50 feet. The damage results in a 
premature shedding of the foliage. Other species of Phyllonorycter 
include P. salicifoliella Chamb., which works in the under side of the 
leaves of willow, poplar, and cottonwood; P. apicinigrella Braun, 
which works in the under side of willow leaves; P. felinella Hein., 
which works in the under side of sycamore leaves in California; P. 
incanella Wlism., which works in both sides of alder leaves; and P. 
arbutusella Braun, which works in the leaves of madronia. 
Cameraria agrifoliella Braun works in the upper surface of leaves 
of coast live oak. C. alnicolella Wlsm. works in the upper surface of 
alder leaves. C. wmbellulariae W\sm. makes blister blotches on leaves 
of California laurel. 
The aspen leaf miner Phyllocnistis populiella Chamb. (fig. 43) 
leaves a labyrinthian trail of frass as characteristic of its work in the 
under side of aspen and poplar leaves. 
Common leaf miners in live oak include Bucculatrix albertiella 
Busck and Abebaea subsylvella W\sm. 
SAW FLIES 
Sawflies form another important group of leaf-eating insects that 
in Many cases cause extensive defoliation and destruction of timber. 
In the Northern States and in Canada, such species as the larch saw- 
fly, the European spruce sawfly, and the jack pine sawfly have been 
responsible for the death of as much as 85 percent of the stand over 
thousands of acres. In the West the native sawflies occasionally de- 
velop widespread outbreaks and may cause heavy defoliation over 
hmited areas, but the total timber destruction so far has not been 
reat. 
5 The sawflies (fig. 44) belong to the order of wasps (Hymenoptera) 
but in appearance are usually more like flies than wasps. They have 
thick, cylindrical bodies with four membranous wings, the hind pair 
somewhat smaller than the forewings. The head, thorax, and base 
of the abdomen are nearly equal in width. They range in size and 
color from small grayish insects not over one-fourth inch in length 
to large, showy species (Cimbew) over 1 inch long. They are called 
sawflies because of a sawlike attachment which the female carries 
at the tip of the abdomen and uses to slit open leaves or stems for 
the reception of her eggs. Usually only one egg is deposited in each 
slit, but as many as 14 or more punctures may be made in a single 
pine needle. 
The larvae resemble hairless caterpillars except that most of them 
have from six to eight pairs of abdominal legs, or larvapods, on the 
abdominal segments, in addition to the usual three pairs of true legs 
on the thoracic segments. Because of their resemblance to cater- 
pillars the larvae are sometimes called “false caterpillars”; and since 
many are wormlike and often slimy, they are called “slugs” or 
“worms.” Most of them are typical external leaf chewers, but a few . 
are leaf miners and even gall makers. 
One of the most characteristic features distinguishing sawflies are 
the cylindrical, papery, capsulelike cocoons which the larvae fre- 
