INSECT ENEMIES OF WESTERN FORESTS 49 
contain only one or two young in each chamber, and when the in- 
sects emerge the galls flare open, and the scales drop from the twigs. 
The alternate form attacks western white pine and is easily recog- 
nized by the waxy secretion that appears as a whitish-gray mold on 
the bark and needles. The attacked foliage is apt to be sparse and 
stunted; the needles fall prematurely, and the fascicles or bundle 
sheaths are left protruding from the limbs as short spurs. The dam- 
age is most frequently found on young white pines. In the last few 
years it has become a rather important enemy of white pine seedlings 
in eastern Washington, Idaho, and western Montana. The adults 
appear as little hemispherical, brown scales one-sixteenth of an inch 
in diameter, with a fringe of white hairs. The head and thorax are 
completely covered by this shield. The life history has not been 
thoroughly worked out, but 1s supposed to be as follows: Eggs are 
laid for the new generation early in the summer. These soon hatch 
and the young bark lice start sucking the juice from the white pine 
twigs. Part of these insects develop wings and fly to the spruce, 
where they construct the terminal cone-shaped galls. The others 
grow and reach the adult stage by the following spring. 
Pineus boycet Annand makes similar galls on Engelmann spruce in 
Oregon and Montana. The needles with enlarged bases are pressed 
closely against the twigs and form intercommunicating chambers in 
which about 15 nymphs are found. The alternate host is not known. 
Pineus bornert Annand feeds on the needles and twigs of Monterey 
pine in California. 
Pineus coloradensis Gill. causes dense mats of dirty wax, covered 
with mold, to form on the twigs of various pines, including ponderosa 
pine, lodgepole pine, pion, white pine, sugar pine, and single leaf 
pinon. It is found in Washington, Oregon, California, and Colorado. 
Pineus similis Gill. is found forming cone-shaped galls on blue 
spruce and Engelmann spruce in Colorado, Oregon, and British 
Columbia. The galls are shorter and thicker than those of Adelges 
cooleyi, and the chambers are intercommunicating. An alternate host 
is not known. 
SCALE INSECTS 
(Coccidae) 
Scale insects form one of the most abundant and variable groups 
of sap-sucking plant enemies. The young are mobile, small, and 
inconspicuous, but unlike most other insects, after they have become 
attached to a plant they lose all power of locomotion. They develop 
a hard epidermis, a thick waxy covering, or a round or oblong shell, 
and remain fixed in one position until they die. It is the female that 
causes all of the injury to plants. The adult males often have wings, 
eyes, antennae, and legs, but no mouth parts and so cannot take food. 
They live only for a short time and are rarely seen. A large number 
of species of scale insects infest nearly all forms of plant life, but 
only a few of those that feed on forest trees are of major importance. 
Scale infestations on conifers, particularly those of the pine leaf 
and California pine scales, are often associated with conditions where 
dust and smoke occurs regularly in the atmosphere. Heavy scale 
attacks on ponderosa pine trees bordering dusty roads have been 
frequently observed as well as on trees exposed to air currents which 
136650°—38——-4 
—_— 
—- 
a 
S 1 is oes ere 
Q a 
| er oe 
ee ree 
m= > = 
xy | 
- 
cur 
= 
oe nS eee Sas 
ee Ga Se eA LAT 
e: 
thie 
eae 
- 
7, 
3 
