Ai 



Discussion. 



G. A. K. Marshall stated that he had visited the W. Indies 

 during the past winter in order to interest the local Governments 

 in the furtherance of a central organisation formed by the Colonial 

 Ofíice, the Entomological Research Committee, for the encourage- 

 ment of the study of injurious insects in the British Colonies. 

 He gave some account of his observations on the sugar cane 

 chafer, Phytalus smithi, in Barbados, which had led to the dis- 

 covery b}^ Mr. NowELL that the species was being controlled in 

 that island by Tiphia parallela, a Scollid wasp. This discovery 

 had been communicated to the Government of Mauritius, where 

 the chafer had been doing very great damage to sugar, and it 

 was hoped that it might be possible to introduce the parasite 

 into that island. Mr. Marshall referred to Mr. Ballou's 

 statement that the Phytalus might be either indigenous in Bar- 

 bados or introduced, and stated that the evidence available made 

 it practically certain that the species was indigenous in the 

 W. Indies, and had been introduced from there into Mauritius. 

 R. Newstead commented on the control of certain pests 

 mentioned by the author, and laid emphasis upon the fact that 

 it seemed quite evident that fungi thrived best in a damp, humid 

 atmosphere, rather than in a dry one. In reference to Eriophyes 

 he asked whether sulphur in any form had been tried as a remedy. 

 A. T. GiLLANDERS Said that as regards parasites the Board 

 of Agriculture in this country had been experimenting with an 

 insect which was doing much damage to the larch crop, viz. 

 Nematus erichsoni. They had gathered the cocoons, killed on 

 the perfect insects, and let the parasite, Mesolius aulicus, out 

 in the infested area. This had the effect of reducing the pest to 

 some extent . Personally, however, he believed that better cultural 

 methods would do much to eradicate the pest. The larch is a 

 tree which, in consequence of its very light foliage, gives very 

 little shade to the ground. Thus when grown as a full crop the 

 surface conditions of grass and moss were ideal for the breeding 

 of the insect, whereas if the crop were mixed with beech or other 

 shade-bearing trees, the surface conditions accruing from this 

 mixture would be such that the insect could not pass through 

 the pupal stage. 

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