337 



GoLoviAXKo (Z.). Ktj Bonpocy BMflOBbixi* M BospacTHbixTj npM3Ha- 

 KaXTj nMMMHOKTj MclolonthamdoloniJia, L. {vulgaris, F.) M Melolontha 

 hippocastani, F. [On the question of the specific and age characters 

 of the larvae of Melolontha melolontha, L. {vulgaris, F.) and M. 

 hippocastani, F.]— «PyccKoe 3HTOMonorM4ecKoe 06o3ptHie.» 

 [Revue Russe d^Entomologie], Pctrograd, xiv, nos. 2-3, 14th 

 October 1914, pp. 243-253, 19 figs. 



The structure of the mandibles of the larvae of Melolontha melolontha 

 and M. hipjjocastani is described, the object being to estabhsh, if 

 possible, a method of distinguishing these larvae. It appears that the 

 mandibles of the larvae of the two species immediately after moulting 

 are absolutely indistinguishable ; the jaws at that time differ greatly 

 from those of the period before moulting ; in the great majority of 

 cases differences in the structure of the jaws could be observed in 

 larvae found a long time after moulting or immediately before moulting 

 or pupation, but this difference is thought to be due to the varying 

 nature of the soil in which the larvae were found. As the larvae of 

 M. melolontha usually occur in clay soil and those of M. hippocastani in 

 sandy soil, these differences may be useful for the recognition of the 

 species in some cases. The difference in the construction of the man- 

 dibles before and after moulting may serve as some indication of the 

 age of the larvae in conjunction with the following data as to the sizes 

 of the head of the larva of M. hippocastani : — During the first year 

 of the hfe of the larva the width of the larval head is 0'25 mm. and 

 the height 0'15 mm. ; during the second year of Ufe the width of 

 the head is 0*4 mm. and the height 0-25 ; during the third year the 

 width is 0'65 and the height 0*4 mm. Figures are given illustrating 

 details of the structure of the mandibles at different periods. 



Smirnov (D). MeTOflaxT» 6opb6bi ct> opeAHbiMM HactKOMbimn. [On 



the methods of control of insect-pests.] — « PyCCKOe SHTOMOnorM- 

 HeCKOe 06o3p'feHie.» [Revue Russe d' Entom.ologie\ Petrograd, xiv, 

 nos. 2-3, 14th October 1914, pp. 332-337. 



The methods for the control of insect pests may be divided into 



(1) direct destruction — i.e., the poisoning or mechanical destruction 



of the pests ; (2) indirect destruction — i.e., by means of parasites, fungi 



and bacterial diseases ; and (3) preventive remedies. The first type of 



remedy is the most in use at the present time, but is frequently very 



difficult of application and not always effective. It is often expensive 



in case of frequent outbreaks of pests of field crops and is sometimes 



harmful to plants. The remedies of the second group are still in- 



ssufiiciently studied. A more general use of various preventive remedies, 



hich can be devised from the knowledge of the life-histories of various 



>ests, is advocated, especially rotation of crops and various preventive " 



levices such as trenches against Hylobius abietis, L., and caterpillars 



of Euxoa segetum, Schiff., etc. The selection of pest-proof strains of 



lants is especially advocated as affording a guarantee against 



•°,quent damage and not requiring the constant use of expensive 



'^es, materials and labour. ." ;.^i .' 



t.P12/91. 1.500. 7.15. B.&F.Ltd. Gp.11/3. A 



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