66 



Tragardh (I.). Bjorksplintborren ock tradoiaren tva fiender till vara 

 bjorkdungar. \Scolytus ratzebiirgi and Cossus cossiis, two Enemies 

 of our Birch Groves.]— Lustgdyden, Arsskrift for Dendrologi och 

 Parkvdrd, ii, 1921, pp. 119-127, 10 figs. 

 Scolytiis ratzeburgi does not breed in felled birch trees or in wood 

 cut for fuel, and is therefore much scarcer and less often injurious to 

 birches than the common bark-beetles of spruce and fir are to those 

 trees. Nevertheless, this beetle may attack and finally kill quite 

 healthy trees, if wood from birches infested in the forest is stacked 

 year after year in the close vicinity of birch plantations. Such an 

 attack was studied by the author in 1920. Some unhealthy birch 

 trees were found to have a number of large, oval wounds through 

 the bark ; these were old egg-galleries of the bark-beetle. On one 

 tree, about 45 ft. high and about 12 in. in diameter, at breast-height, 

 125 such holes were found in different stages of development. Of 

 these 40 were old egg-galleries where no eggs had hatched, 46 were 

 egg-galleries with more or less developed larval galleries, in which, 

 however, no larvae had become full-grown, six were egg-galleries 

 from 1919 with fully developed larvae or pupae, and 29 were new 

 galleries containing newly laid eggs. Some of the old wounds were 

 more than 14 years old, and it is evident that these birches had been 

 repeatedly, perhaps annually, attacked by the beetle emerging from 

 the infested fuel wood stacked in the vicinity. 



Cossits cossus during recent years has often been found in 

 birch trees in Sweden. The author beheves that it is essential in 

 the case of this moth for the bark of the attacked tree to be already 

 injured. Consequently the young larvae are frequently found in the 

 galleries due to other insects, such as those made by Cryptonhynchus 

 lapathi. Moreover, it is evident that the moth in ovipositing prefers 

 trees already attacked by the larvae, it being common to find larvae 

 of several different broods in the same trunk. 



Granlund (F.). En farlig parasit. [A Dangerous Parasite, Xyleborus 

 dispar.] — Sveriges Pomologiska Forenings Arsskrift, xxii, 1921, 

 pp. 146-148, 2 figs. 

 A popular account is given of the hfe-history and the damage done 



by this beetle. Apple, pear and cherry trees are attacked, preferably 



young trees, under 20 years old. Cutting off and burning the infested 



branches is recommended as a rem.edy. 



SCH0YEN (T. H.). De almindeligste skadeinsekter paa landbruks- 



planterne. [The most common Agricultural Insect Pests.] — 

 Christiana, 1921, 52 pp., 41 figs. 

 This text-book for the use of agricultural schools contains chapters 

 on the following subjects : — The relation of insects to cultivated 

 plants ; prophylactic measures ; direct control measures, traps, chemical 

 methods, etc., and the classification and development of the various 

 orders. 



A key to the insects is appended, arranged according to the plants 

 attacked and to the nature of the injury. 



DiFFLOTH (P.). Comment lutter contre les Ennemis des Arbres 

 d'Ornement. — La Vie Agric. & Rur., Paris, xix, no. 48, 26th 

 November 1921, pp. 377-380, 4 figs. 

 Ornamental trees are particularly fiable to insect attack, as they 



lose in transplanting all the advantages of their natural habitat in 



