REVIEWS 435 



ting, the effect of the attacks on the crown on the growth and trunk 

 formation, and the geographical distribution and rate of propagation 

 of the two kinds of pine beetles in different parts of the country, and 

 the best method of preparing trap trees. 



Investigations into bark beetles. Continued studies of the distribu- 

 tion, biology, and importance of the different species in the various 

 parts of the country. Studies of the development of the bark beetle in 

 spruce and its connection with the climatic factors and the consequent 

 importance of the time of cutting. The best method of preparing 

 trap trees to be investigated. 



Investigations into insects injurious to spruce and pine cones. These 

 shall be continued according to the same plan as before, supplemented 

 by investigations into the cone fauna during the summer. Experiments 

 on the possibility, by investigating spruce cones in the summer, of 

 predicting the quality of the cones, and experiments in killing the 

 larvae of the spruce-cone moth by hydrocyanic acid. 



Investigations upon insects injurious to forest-tree plants in nur- 

 series. Investigations into saw flies and other injurious insects that 

 may possibly occur. 



Other investigations. The investigations that have begun upon 

 Bupalus ptniarius should be continued. 



Studies in the importance of Pissodes and Magdalis, especially on 

 the pine heaths of Norrland. 



Studies in certain technical damage-doers, such as those done by the 

 Lamia sutor and Tetropium and in means of fighting them. 



Commencement of studies in the sazv flies of pine and spruce trees. 



See also under 5^ and 6. 



TV. RACES OF FOREST TREES AND THE USEFULNESS OF FOREIGN TREES 



IN SWEDEN 



(a) Studies in races of spruce and pine. The cultures which have 

 so far been or will be established of spruce seed collected for this 

 purpose shall be followed and watched carefully (N), and, in addi- 

 tion to this, experiments should be instituted in fertilization with pure 

 races (N). 



(b) German spruce seed. Existing plantations, carried out by the 

 forest authorities with plantings of spruce from different places in 

 Central Europe, shall be sought out and registered (S). 



(c) Larch. The permanent sample plots shall be re-examined 

 when necessary, and thinned, with the object of obtaining yield tables 



