INSECT ENEMIES OF WESTERN FORESTS 33 
In addition to breeding under the bark of twigs and branches, 
adults of the larger species of PAloeosinus have the feeding habit of 
nipping off the leaflets and of feeding by boring into the small twigs 
of various cedars and cypresses. ‘This injury is frequently very 
severe 1n the case of ornamentals and shade trees. 
Broad-leaved trees are attacked by various genera of bark beetles, 
including many species of Micracinae. Oak twig beetles belong 
to the genus Pseudopityophthorus (p. 182). 
TWIG WEEVILS 
Twig weevils, belonging to the family Curculionidae, are often the 
cause of serious damage to the terminals of young coniferous trees. 
The adult female weevil uses her long, curved beak to excavate a 
small pocket in the bark of the terminal shoot in which to place 
her eggs. The young larvae, on hatching, burrow beneath the bark 
and excavate winding tunnnels between the bark and wood. On 
reaching full growth each constructs an oval cell, partly in the wood 
and partly in the bark, in which to pupate. Weevil work is dis- 
tinguished from that of the twig moths in that there is lttle exu- 
dation of resin or pitch, and such as does occur is not mixed with 
webbing or larval castings to indicate the presence of the insects 
under the bark. The first conspicuous evidence of injury is the 
dying of the terminal shoot. 
The two most important genera concerned are Pissodes and Mag- 
dalis. In the Kast the white pine weevil (Pissodes strobi Peck) is 
a well known example of the importance of these insects. In the 
Western States there are several species which do similar damage; 
though not of economic importance as yet, they are almost sure to 
be so when second-growth stands and plantations are more widel 
established. : 
Proper silvicultural methods offer the best solution of the weevil 
problem. Where young trees are grown in dense stands, or under 
the shade of other trees, weevil injury may be negligible. If in 
handling young stands subject to weevil injury the shade of older 
trees can be provided until the young trees reach 25 feet in height, 
or if the young trees can be grown in dense stands until they have 
passed the susceptible period, the damage should be lessened. In 
plantations, where individual care can be given, control can be ob- 
tained by cutting off the infested stems in May and September and 
storing these in wire cages of a mesh small enough to hold the beetles 
but large enough to allow the parasites to escape. If this is done 
for several seasons almost complete control of the weevils should 
be obtained. 
The Sitka spruce weevil (Pissodes sitchensis Hopk.) is the insect 
most injurious to Sitka spruce reproduction in the Northwest. The 
small weevils attack and kill or seriously injure the terminal shoots 
of many young trees, causing a crook in the trunk or a forked and 
worthless tree. Trees from 2 to 8 inches in diameter and 5 to 25 
feet in height are the most susceptible to attack. The species is 
distributed throughout the range of Sitka spruce. 
The adults are light to dark brown, oval-shaped beetles, about 
three-sixteenths of an inch in length, with a prominent curved beak. 
136650°-——38——3 
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