INSECTS AFFECTING FOREST TREES. 533 



to pine attacked by bark borers but also to hickory infested by the dangerous 

 species which has proven so injurious in New York in recent years. The thing to 

 be remembered in this connection is that cutting should be done at a time when 

 the insects are mostly within the tree and will therefore be more likely to perish. 

 Tliis is true of all these species in the winter and also of some at certain periods 

 in the svimmer. The sudden dying of a tree in midsummer in the midst of 

 other valued pines should receive immediate attention, and if the bark beneath 

 is inhabited by large numbers of grubs, the infested tree should be cut and either 

 destroyed or the bark removed at once so as to prevent the developing of the 

 insects and a later generation entering other trees. The writer has seen several 

 instances in the vicinity of Albany where such measures could have been adopted 

 to advantage and in all probability might have resulted in saving adjacent trees. 

 Dr. A. D. Hopkins, now of the U. S. Department of Agriculture, has made an 

 extensive study of these insects in various sections of the coimtry, and he recom- 

 mends for certain bark borers that the winter cutting be regulated to include 

 as many of the infested, dying and dead trees as possible, and that the logs of the 

 same be placed in water before June ist. Secondly, that the summer cutting be 

 so regulated that as many recently attacked trees as possible may be cut and 

 the bark removed from their trunks and stumps, and, thirdly, that a large number 

 of trees not infested be girdled where logging operations will be carried on the 

 following summer and winter. The girdled trees may then be felled and the logs 

 containing the young grubs peeled or placed in water before the first of the 

 succeeding June. 



These recommendations of Dr. Hopkins were prepared with special reference to 

 the spruce-destroying species, Dendroctonus piceapirda Hopk., which has been caus- 

 ing severe injury in Maine, and to which he attributes serious damages to spruce 

 forests in earlier years. It does not follow that this is the best time to girdle 

 trees for other species, but the presumption is that the most effective results can be 

 secured by operations conducted about that time. The precise season for different 

 borers must be determined by repeated tests. We know that some are attracted to 

 dying trees, and if we were to produce this condition at about the time when most 

 of them are looking for favorable conditions and then destroy the tree and its con- 

 tained hosts, much would be accomplished. The checking of the destructive bark 

 borers renders it unnecessary to safeguard against species which follow, because they 

 will not attack living trees as a general rule. 



Most of these measures, except protecting birds, have not the slightest effect 

 upon weevils and other insects which work in the tips of our pine trees. It is 



