62 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



y 16 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 is 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. Some 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 boycei 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 borneri Annand feeds on the needles and twigs of Mon- 

 terey pine in California. 



Pineus coloradensis Gill, causes dense mats of dirty wax, cov- 

 ered with mold, to form on the twigs of various pines, including 

 pondersosa, Jeffrey, lodgepole, pinyon, white, sugar, and singleleaf 

 pine. It is found in Washington, Oregon, California, and Colorado. 



Pineus similis Gill, forms cone-shaped galls on blue and Engel- 

 mann spruces in Colorado, Oregon, and British Columbia. The 

 galls are shorter and thicker than those of Chermes cooleyi, and 

 the chambers are intercommunicating. An alternate host is not 

 known. 



SCALE INSECTS 



Scale insects (Coccidae) form one of the most abundant and 

 variable groups of sap-sucking plant enemies (4-7) . 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 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 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 

 needle and black pine-leaf scales, are often associated with con- 

 ditions where dust and smoke are found 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 cur- 

 rents that carry the smoke from mills. The choking of stomata in 

 the leaves by foreign particles probably renders them susceptible 

 to these insects. 



Scale insects are controlled through the use of contact sprays 

 (59), such as miscible oils and distillate or petroleum emulsions, 

 and in orchard work by fumigation. None of these methods are 

 practical under forest conditions, but fortunately none of the scale 

 insects attacking forest trees have become serious enough to call 

 for control. 



