632 



AMERICAN FORESTRY 



is possible to direct the control measures against the 

 weakest point. In the case o{ the budworm this point 

 seems to be the habit of passing the winter as first stage 

 catcqiillars that liave just hatched from the eggs and 

 that are so weak that unless suitable food is present when 

 thev emerge in the spring the cater])illars will soon die. 

 How can this condition be brought about? Knowing that 

 budworm outbreaks start up in isolated spots in the for- 

 est, and that it takes several seasons to gain headway 

 enough to be a real menace to the forest, the most logical 

 control would be for the timberland owner to send a 

 small jobber into this area and clear out the infected 

 stand during the winter. In the spring the young cater- 

 pillars coming out would find nothing but dry tops and 

 would be unable to survive, their food supply having 

 been cut off. Under ordinary conditions this method of 

 control, which is at present being tried out in Maine, 

 would not only be feasible but should pay for itself many 

 fold. In the first place the infestation being located 

 during its early stages would probably allow two seasons 

 leeway to get into the area. The operation should, if 



A TYPICAL FIRE TR.AP 



Type of spruce slope over which the budworm has swept, greatly 

 increasing the fire hazard. 



properly planned, practically, if not entirely, pay for it- 

 self. The protection to the surrounding timber would 

 more than offset any financial loss due to the o])eration. 



As to the bark-beetles it is a common belief that these 

 never attack green, healthy trees this is a complete fal- 

 lacy. In the normal forest it is not necessary for the 

 beetles to attack the healthy green trees which are not 

 particularly suited to their wants, owing to the fact that 

 there are usually enough sickly trees or green windfalls 

 to supply suitable feeding and breeding places. Large 

 areas of sickly trees due to defoliation, or areas of green 

 windfalls or even green slash mean that the bark -beetles 

 will multiply rapidly. Ordinarily the outflow of sap or 



resin caused by the feeding of the bark-beetle drowns 

 them, thus preventing their increase. In sickly or weak 

 trees the flow of sap is much lessened and is not a seri- 

 ous detriment to the development of the beetles. It can 

 readily be seen, however, that any great outflow of saj) 

 caused by the attack of the bark-beetles would so weaken 

 the trees that they would become suitable breeding and 

 feeding grounds. This is exactly what takes place dur- 

 ing a bark-beetle epidemic and the trees are killed just 



THE FOOD OF THE BUDWORM 



Type of spruce and fir growth in which the spruce budworm and 

 bark-beetles create great havoc. 



as surely as if they were felled, the galleries made by the 

 bark-beetles cutting off the flow of saj). There are two 

 main reasons for the bark-beetle outbreaks. First in im- 

 ])ortance is the weakening of vast nuinbers of trees by 

 the budworm in which the bark-beetles find favorabk- 

 conditions for feeding and increasing. The second cause 

 is the large amount of fresh slash left after cuttings. 

 The time has apparently not come when slash disposal 

 is practicable here in Northern Maine although it is 

 being carried on on a large scale in Canada. 



Outbreaks of bark-beetles can usually be controlled 

 without great difficulty. The habits of the bark-beetles 

 render them vulnerable by the only method that lum- 

 bermen could economically employ. The removal and 

 utilization or burning of the trees is the most satisfac- 

 tory control and an infestation can be checked in a single 

 season. Floating the logs early in the spring, as is the 

 usual custom, destroys the beetles. When only a portion 

 of an infestation can be treated, control measures should 

 be concentrated against the centers of infestation. Re- 

 markable work is being carried on in the West in the 



