665 



entirely free from the pest, but a few oat plants among it were attacked ; 

 thus apparently " evene " is immune. The damage in Almkerk was 

 very serious, but the land was in a bad condition. In France the 

 damage done in different years on various soils is very variable ; accord- 

 ing to Guille, it is not uncommon in some years to find fields in which 

 every plant is attacked and the yield reduced to 25 per cent, or even 

 nothing. Tarsonemus spirifex appears to prefer oats to all other grain ; 

 Marchal records it on a few wheat ears, and Guille occasionally on 

 barley ; Kirchner regards barley as immune ; it has not yet been 

 found on rye. The sudden appearance of the mites cannot be explained 

 until more is known as to how and where this pest passes the winter ; 

 this may be as fully developed mites or as larvae in the soil. According 

 to Kirchner, Guille and Schneider, oats following oats were more than 

 ordinarily attacked, and this is borne out in the experimental fields 

 at Wageningen, on which oats have been grown continuously for nine 

 years. Guille thinks that the mites migrate to wild grasses after the 

 oats have been cut ; another possibility is that eggs remain in the 

 spikelet and are sown with the seed ; but the author regards it as 

 more than probable that grasses allied to oats are also food-plants 

 and that they resist attack better than oats. Helping the plants over 

 the critical time seems to be the only method of combating the pest. 

 This can be done by a dressing of nitrate of soda. Proper rotation of 

 crops, correct preparation and manuring of the soil, and early sowing 

 should also be of use, in that the plants will be in a better condition 

 to resist attack. It has been noticed in France that oats suffer most 

 on soils subject to drought, not merely want of rain bnt want of 

 power to retain moisture. At Wageningen the months of May and 

 June were remarkably dry, and had the oats been sown earlier, they 

 would have obtained a better and larger root-hold to enable them to 

 stand the want of water. Wet weather is inimical to the mites directly, 

 and indirectly favours the growth of a fungus which attacks and kills 

 them. This fungus has not been determined, but it greatly resembles 

 Cordyceps clavulata, FjIHs. 



A description of the mite and larvae with plates by Dr. A. C. 

 Oudemans forms a supplement to this paper. 



Trinchiert (G.). La "Tortrice Buoliana" [Evetria huoliana). — ■ 

 Reprint from Bulletino A.O.P.I., >Sanremo[?], iii, no. 7, July 1915, 

 7 pp. 



In consequence of the recent United States quarantine measure 

 prohibiting the importation of pines of Europear. origin [see this Review, 

 Ser. A., iii, p. 549], this paper has been prepared in order to give, in a 

 popular form, information regarding Rhyacionia {Evetria) buoliana 

 (European pine-shoot moth). The 15 works mentioned in the 

 bibliography include the two recent papers by Busck [see this Review, 

 Ser. A, ii, p. 701 ; iii, p. 376]. 



ScARiOLi (D. G.). Gli Afidi. [Aphids.] — Venezia Agricola, Venice, 

 xviii, no. 32, 8th August 1915, p. 3. 



Injections of potassium cyanide are ineffective against Aphid attack 

 [see this Review, Ser. A, iii, p. 73] as the insects only refrain from 

 infesting those portions of the plant which are perishing through the 



