435 



therefore, are advised to take care that the seeds, when planted, are 

 always covered with soil. Care must be taken also in planting already 

 germinated seeds received from other plantations ; such seeds should 

 first be planted under fine meshed wire gauze and any flies that appear 

 killed. Hitherto this pest has only been detected on two tea-estates, 

 but it is considered possible that it occurs elsewhere, the damage to 

 the seeds being attributed to fungus disease. 



TuLLGREN (A.). Potatisodlingens viktigaste flender inora djurvirlden. 



[The most important potato pests.] —Trddgar den, Stockholm, 

 March 1915, h. 3, p. 8486, 2 figs. 



This is a short review of the most important insect enemies of 

 potatoes in Sweden and deals with wireworms, the larvae of cock- 

 -chafers, cutworms, Tipulids, Uydroecia micacea, Esp., Lygus pabuloruni, 

 Mey., [sic] and Blaniulus guttulatus, Gerv. 



Tragardh (I.). Hvarpa beror bladminerarnes formaga attorn hosten 

 konservera klorofyllet i bladen ? [On what depends the abihty of 

 the leaf-miners to preserve the green colour in the autumn mines ?] 

 — Skogsvardsfdreningens Tidakrift, Stockholm, March 1915, h. 3, 

 pp. 179-190, 5 figs. 



In order to test the generally accepted hypothesis of Wood, that 

 leaf-miners produce some preservative substance in order that the 

 part of the leaf occupied by the mine should retain its green colour a 

 long time after the rest of the leaf has withered, the author examined 

 two mines of different types found on oak leaves — viz., those of 

 Lithocolletis sp. and of Nepticula subbimaculella. The anatomy of the 

 mines and their mode of construction was investigated, and the 

 conclusion was arrived at that there is no necessity to assume the 

 existence of any preservative substance produced by the leaf-mining 

 larva in order to explain the persistence of the green colour in the 

 mines and that this phenomenon is brought about by the damage done 

 to the vascular system at a period when the sap is flowing back from 

 the leaves to the trunk. 



Tragardh (I.). Barrtradskvalstret {Paratetranychus ununguis Jac). 

 [The pine-tree sip'mning-mite.y-Skogsvardsfdrenirigens Tidskrift, 

 Stockholm, March 1915, pp. 242-246, 1 fig. 



The eggs of this species hibernate in crevices of the bark and hatch 

 at the beginning of May, about four generations occurring during the 

 summer. It attacks pine, fir and larch. Attacks have been recorded 

 from nurseries near Bastad in July 1914, when Picea excelsa, P. alba, 

 P. sitchensis and P. engelmanni were damaged, and from Reftele, 

 where, at the same time, 5-6-year old plants of Picea alba were injured. 

 P. ununguis is also found in forests under circumstances which prove 

 that it is indigenous to Sweden. Spraying with soap emulsion or 

 quassia-nicotine emulsion is recommended ; larches may be sprayed 

 in winter with 5 per cent, carbolineum. 



(C180) b2 



