230 



insect pests and the instruction of the population in the use of various 

 remedies, while scientific studies and researches are conducted in 

 connection with pests which have a special importance. The Bureau 

 has also conducted a campaign against the rodent, Spermophtlus 

 citellus, w^hich has been proved to be a carrier of plague, and as such, 

 is particularly dangerous in the eastern part of the government, 

 adjoining the province of the Don. Owing to the great importance 

 of these rodents, the author urges the necessity of the Zemstvos and 

 the Central Government undertaking a campaign against them ; 

 the latter has already assigned £100,000 for this purpose, while many 

 Zemstvos have also created special funds for the same object. 



Andreieva (N. V.) & KuRDjuMov (N. v.). BjiiflHie noepemfleHifl 

 flpoBbixii xntOoBii ujBeACKoPi myLUKO^ m flpoeoii nyxoM Ha pocTi* 

 M ypowail paCTeHJM. [The effect of the injuries to summer-sown 

 crops by the Swedish fly {Oscmella frit) and by Chortophila 

 genitalis, Schnabl, on the growth and yield of the plants.] 

 pp. 25-36. 



The investigations described in this paper were conducted during 

 the summer of 1913 at the Experimental Station of Poltava. The Frit 

 fly winters in the larval stage and usually appears late in summer 

 when the summer-sown crops begin to tiller. The females oviposit 

 mostly on young stems and therefore never injure the main shoot 

 of grain sown at a normal time, but only the later side-shoots. 

 Oviposition is usually efl:ected on strong plants, such as tiller freely 

 and for a longer time, thus providing more young stems suitable for 

 that process. The life-history of CJwrfophila (Adia) genitalis is 

 different, there being only one generation yearly. It winters in the 

 pupal stage and appears with the first warm days in spring ; thus when 

 the shoots of summer-sown wheat appear, on which the larvae feed, 

 the flies are already in the fields and are able to complete their 

 oviposition before the wheat begins to tiller. Therefore only the main 

 stem of each plant is infested. The nature of the injury is the same 

 as that caused by Oscinella {Oscinis) frit . The results of a comparative 

 investigation of plants damaged by each of these pests and of 

 healthy plants are described. The sample plants for these inves- 

 tigations were taken from the same fields and as far as possible amongst 

 plants situated close to each other. The results are shown in tables, 

 containing figures relating to 50 plants of summer-sown wheat infested 

 by C. genitalis at the time the stems become hollow, and 50 healthy 

 plants, samples of both having been taken on 14th May. The infested 

 plants showed a tillering increased by 10- 1 per cent, as compared with 

 the healthy ones, the later side-shoots having increased by 67- 1 per 

 cent. ; the average length of the stems was 15-3 per cent, less ; the 

 weight of the green plants was 17-8 per cent, less, and that of the dried 

 ones 18-5 per cent. Another table deals in the same way 

 with infested and healthy plants of summer-sown wheat taken when 

 they were coming into ear, and the results show that the tillering of 

 the infested plants had decreased by 8-9 per cent. ; the number of 

 plants producing ears had decreased by 32-6 per cent. ; the average 

 length of the stems was 11 per cent, less; the weight of the green 



