106 A MANUAL OF FORESTRY 



July and August, after which the imprisoned beetles bore a way 

 out to freedom and seek suitable abodes in which to pass the 

 winter. 



Treatment. The best way to fight this enemy is to cut off 

 the infested top during June, July or early August, before the 

 beetles have escaped. The surest way of extermination is to 

 burn these tops, but as they often are the habitat of minute 

 insects which prey upon the weevil, a modification has been 

 suggested by Dr. Hopkins of the United States Bureau of Ento- 

 mology. Obtain a perfectly tight box or barrel with but one 

 opening (a large metal can is still better). In this, place the 

 infested tops, and cover the opening with a very fine-wire mesh 

 (one which an ordinary pinhead cannot pass through). The 

 beetles cannot escape, but the parasites easily make their way 

 out and attack other weevils. The box must not be exposed 

 to the weather as it will check and allow the weevils to escape. 

 Either form of treatment must be repeated several successive 

 years as it is impossible to exterminate them in a single season. 



In order to prevent the injured trees from developing two or 

 more main stems, all of the side branches of the top whorl, except 

 one, should be cut off close to the main stem. This one side 

 branch will straighten and develop into the trunk of the tree. 



PINE-BARK APHID (Chermes pinicorticis). 



Form of Damage. This plant louse is sometimes present in 

 such large numbers on pine stems as to weaken the vitality of 

 the tree by sucking the sap. A sickly condition and occasionally 

 death, in the case of young trees, results. This aphid occurs 

 everywhere throughout the range of the white pine. 



Appearance. A cottony appearance on the twigs and some- 

 times over the trunk of the tree betrays the presence of the 

 insect. It is sometimes mistaken for the exudations of the 

 pitch. 



The eggs occur in downy balls near the base of the needles 

 and vary in number from five to sixty or more in each cluster. 

 They are oval, and of a reddish yellow color. As insects some are 



