432 



Although these experiments cannot be considered conclusive, they 

 undoubtedly show that locusts onty succumb to concentrations above 

 0-1 volume per cent. The liberation of gas must be continued for 

 at least 15 minutes. 



KuLAGiN (N. M). noHBneHMM CapaHseBbix b XVIII m XIX 



ClOJieTHflX B EBpone. [The Occurrence of Locusts in the 

 Eighteenth and Nineteenth Centuries in Europe.]- — TpyAbI 2ro 



BcepoccMMCKoro SHTomo-OmonaTojioriiHecKoro C"be3fla b nerpo- 

 rpafle, 25-30 OkthOph 1920 rOfla \Proc.2nd All- Rtcssian Entowo- 

 Phvtopath. Meeting in Petrograd, 25th-30th October 1920], 

 Petersburg, 1921, pp. 109-122. [Received 21st June 1922.] 



The object of this paper is to amplify previous records [R.A.E., 

 A, V, 100] by the addition of Russian ones, as well as those of the 

 neighbouring countries. 



From the available material it is evident that a periodicity of 

 appearance cannot be established either for Europe in general or for 

 any particular country in Europe. The absence of such periodicity 

 is due to the complexity of the factors influencing the maximum 

 reproduction of these insects. Locusts, having once appeared 

 en masse, generally remain in large numbers for two or three years 

 at least. Maximum reproduction is usually observed in warmer 

 years, although some species may appear en masse at comparatively 

 low temperatures. Humidity is one of the essential factors in their 

 development. 



DoDRODEEv (A. I.). ripocflHOM MjiM KyKypysHbiM lAoTb\ne\{ {Pyrausta 

 nubilalis, H lib.). —TpyAbI 2ro BcepoccMMCKoro 3htomo-Omto- 

 naionorMHecKoro CijeaAa b FleTporpaAe, 25-30 0KTfl6pfl 1920 roAa 



[Proc. 2nd All-Russian Entomo-Phytopath . JMccting in Petrograd, 

 25th-30th October 1920] , Petersburg, 'l921 , pp. 1 23-1 28. [Received 

 21st June 1922.] 



An account is given of the life-history of Pyrai(sta nubilalis, Hb., 

 the damage caused by this moth and the general remedial measures 

 for it. In the Don district two generations a year generally occur, 

 but in Voronezh only one has been observed. 



The collection of eggs is advocated in infested kitchen gardens, 

 and wherever the more intensive cultivation of valuable plants is 

 practised. 



Of the natural enemies a Tachinid has been found in the Don 

 district and a Chalcid near Voronezh, but they have not yet been 

 identified. 



Velitchkevitch (A. L). K BuonorMM Myx, MMHypyicinMx JiMCTbfl 

 3jiaK0B B HoBfOpOACKOM ry6epHMM. [On the Biology of FHes 

 Mining the Lca\cs of Graminaceae in the Novgorod District.] — 



TpyAbI 2ro BcepoccMMCKoro SHTOMo-OmonaTOJiorMHecKoro CT>e3Aa 

 B rieiporpaAe, 25-30 0KTfl6pfl 1920 rOAa [Proc. 2nd All-Russian 

 Entomo-Phytopath. Meeting in Petrograd, 25th~30th October 1920], 

 Petersburg,'l92l, pp. 129-135. [Received 21st June 1922.] 



This paper endeavours to rouse greater interest in the study of insects 

 mining in the leaves of various- Graminaceous plants. Agromyza 

 scutellata. Fall., and A. pusilla, Meig., which is considered by some 

 authorities to be only a variety of the former, are dealt with in detail. 



