172 



Chortophila hrassicae) is given. The results obtained prove con- 

 clusivelv that they are a very effective means of protection against 

 the attacks of these insects. They are 2| inches square with two 

 slits, a long one from the centre of one edge to a point half an inch 

 beyond the centre of the disc and a short one, three-quarters of an 

 inch long, at right angles to the other in the centre of the disc. The 

 land on which the experiments were made had been partly under 

 cauliflowers the previous year and had suffered severely from maggots ; 

 this was planted with 816 cabbages and 932 cauliflowers, half 

 the number in each case, i.e., the alternate rows, being protected, 

 the rest being used as controls. Of the 466 protected cauliflowers 

 only 24 were lost, as compared with 294 of the unprotected ones. 

 The results obtained with cabbages were even more marked, only 

 one plant being lost out of 408 protected by the discs. Cabbages 

 however appear to be less liable to infestation than cauliflowers 

 as only 13"2 per cent, of the unprotected cabbages were lost as against 

 63"0 per cent, of cauliflowers. 



The best results are obtained if the soil is in a fine friable condition, 

 when the discs are placed in position and if the plants are placed 

 on slight ridges rather than in depressions. The discs should lie 

 evenly on the soil so that the females cannot crawl underneath them 

 and deposit eggs ; they should not be below the surface level, since in 

 wet weather they may become covered with soil and therefore less 

 efficient. They should be placed round the plants directly after 

 planting out, if this is done later than the first week of May. 



Plants protected by these discs have been observed to be larger 

 and to mature earlier than unprotected ones, owing partly to the absence 

 of maggots and partly to the conservation of moisture round the 

 roots. Root maggot infestation is more likely to occur on light 

 soils than on heavy ones. 



A bibhography of 15 references is given. 



Ford (G. H.). Observations on the Larval and Pupal Stages of Agri- 

 otes obscurus, L.. — Ann. of App. Biol, London, iii, nos. 2 & 3, 

 January 1917, pp. 97-115, 1 fig., 1 plate. 



Agriotes obscurus, the larval and pupal stages of which are described 

 fully in this article, is preyed upon by birds (especially the common 

 plover) and moles, as well as by the Carabid beetles, Pterostickus 

 madidus and Nebria brevicollis. It is very free from internal 

 parasites, but has been reported as being attacked by a Hymenopteron 

 and by a fungus {Isaria), though no definite data are available. 

 The larval period lasts probably four rather than five years ; pupation 

 takes place in an earthern cell about a foot below the surface of the 

 soil and the insect hibernates in the adult stage. 



A bibhography of 10 references is given. 



Petherbridge (F. R.). Note on the Attacks of Phyllotreta vittula on 

 Spring Corn. — Ann. App. Biology, London, iii, nos. 2 & 3, January 

 1917, pp. 138-139. 



Phyllotreta vittula was recorded as attacking barley in Wiltshire 

 'in April 1914, and in May 1916 ; a similar attack was noticed at the 

 Rothamstead Experimental Station, where it also damaged oats. 



