41 



fell were attacked by large niiiubers of Dendroetoiins, t])ereby fur- 

 nishing good evidence that between these dates was the proper period 

 (spring of 1900) to girdle the trees to attract the insects. 



Of the twenty-five trees girdled on the other dates— May 21), June 

 r.), July 11, and September 1 — only seven were attacked by snfticient 

 numbers to kill the trees. 



'rh<^se results, together with observations bj^ tlie author during tlie 

 investigations on the dates of tlie appearance of the leaves and flowers 

 on different trees, indicate tliat the b(?st period to girdle spruce trees 

 to attract the siu'uce-destroying beetle away from other trees may 

 vary with the seasons, but will l)e about ten days, commencing 

 when the catkins (flower stems) are falling from the birches, and con- 

 tinuing while the fire cherry and the hobble bush are in flower. 

 Another good guide will be to commence when the first pupse of the 

 destructive beetle commence to ai)pear in the bark and continue until 

 the beetles commence to fly. 



SUGGESTIONS AND RECOMMENDATIONS. 



The prime ol)jects of tlie in\ estigation were not only to determine 

 facts relating to tlie causes of the death of tlie spru<*e, but to of)iain 

 e\ idence on wliicli to base suggestions and recommendations for 

 mitigating or controlling the ravages of the spruce-destroying beetle; 

 .,i-e\ enfing tlie total loss of the vast amount of timber already killed, 

 and for reducing or preventing the losses from its I'avages in the 

 future. 



It has seemed a hopeless undertaking to determine practical 

 methods of combating invasions of destructive insects in a vast 

 wilderness of virgin forest, or to accomplisli much toward prevent- 

 ing total loss of the millions of feet of timbei* killed or injured b}" 

 them, especially in a country like oui-s, whei'e improved forestry is in 

 its infancy. l>ut with a knowledge of the principal depredator, its 

 habits, its life history, its enemies, and the conditions, favorable or 

 unfavorable, for its destructive work, facts have been determined on 

 whicli to l)ase conclusions relating to simple, inexpensive, and prac- 

 tical methods of coml)atiiig the insects and preventing a large part of 

 the losses. 



It then rests with the owner of tlie property to study the practical 

 features of the problem and the facts determined by the investigator, 

 in order that he may intelligently apply the recommendations to the 

 varying needs and conditions a-s in each case seems most advisable. 

 It should be remembered that it is the investigator's mission to deter- 

 mine the facts and evidences, and present them with recommenda- 

 tions and suggestions, while tlie owner of the damaged or tlireatened 

 property must study and utilize or discai-d tliem, as his jiracti- 

 cal judgment and business interests may indicate is best in each 

 particular case. 



