130 THE CULTIVATED EVERGREENS 



injury restricted to individual branches. The insect passes 

 the winter in cocoons under trash on the ground. There is 

 only one generation a year. 



On small trees, jarring the larvae on to ascreen or some similar 

 device is a good method of control. On larger trees the larvae 

 may be killed by spraying with arsenate of lead at the rate of 

 three pounds of powder to one hundred gallons of water. 



Pine bark aphid {Chermes pinicorticis. Fitch). 



White pines growing under more or less adverse conditions 

 are especially subject to attack by a small reddish aphid which 

 is rendered very conspicuous by a covering of white waxy 

 material. Scotch and Austrian pines are sometimes slightly 

 infested, but the injury is negligible. The insects confine their 

 attack to the smooth bark of the trunk and branches and 

 congregate at the base of the needles. Badly infested trees 

 become sickly, the leaves turn yellowish and in severe cases 

 the tree may die. 



The aphid passes the winter on the bark under the pro- 

 tection of the mass of wax. Early in the spring a cluster of 

 eggs is deposited. The eggs hatch in April and May, the young 

 scatter over the bark, settle down, and become covered with 

 a mass of waxy white threads. On badly infested trees the 

 bark has the appearance of being whitewashed. There are 

 several generations during the season. It is quite probable 

 that this plant-louse has an alternate food plant, but this phase 

 of its life history has not been studied. 



The pine bark aphid may be controlled satisfactorily by 

 thorough spraying with kerosene emulsion — one part of 

 standard stock emulsion in nine parts of water. When good 

 water pressure is available, the pest can be held in check by 

 washing the trees with a stiff spray of clear water. 



