June 17, 1920] 



NATURE 



503 



' rtificates of freedom from pests — a view afterwards 

 upported by several others who took part in the dis- 

 cussion. Mr. H. J. Elwes, however, remarked that 

 a lon^» experience in cultivation had convinced him 

 that needless interference with freedom of import 

 had sometimes been exercised by the authorities. 

 On the chairman's suggestion, a sub-committee 

 was appointed to consider the establishment of an 

 Empire Convention on the subject. 



"The Education of Economic Entomologists," the 

 subject for discussion at the next morning meeting 

 presided over by Prof. Poulton, was introduced by 

 Prof. H. Maxwell Lefroy (Imperial College of 

 Science). Prof. Lefroy advocated the establishment 

 of entomology as a subject independent of general 

 zoology, arid, describing the courses in his own college, 

 emphasised the necessity of a broad scientific training 

 in physics, chemistry, and biology before the 

 specialised entomological work could be profitably 

 taken up; men with exceptional aptitude, however, 

 might be admitted direct to advanced entomological 

 studv. The discussion was continued bv Dr. R. J. 

 Tillyard (Nelson, N.Z.), Dr. R. Stewart "MacDougall 

 (Edinburgh), Mr. F. Balfour Browne (Cambridge), 

 Prof. R. Newstead (Liverpool), Prof. G. H. Carpenter 

 (Roval College of Science, Dublin), Prof. R. D. Watt 

 (Sydney, N.S.W.), and Mr. F. V. Theobald (Wve). 

 While some doubt was, expressed as to the advisability 

 of divorcing entomology from general zoological study, 

 there was general agreement as to the need of a 

 sound and comprehensive scientific training, and 

 several of the speakers insisted further that all entomo- 

 logists in direct contact with cultivators ought to have 

 practical knowledge of farm or garden work. 



On Monday morning, June 7, Sir Daniel Morris in 

 the chair, ^ir. H. A. Ballou (Entomologist to the 

 Department of .Agriculture for the West Indies) opened 

 a discussion on "The Resistance of Plants to Insect 

 .Attacks." He believed that in many cases perfectly 

 healthy plants do not afford the best possible condi- 

 tions for the life of sucking insects, while the food 

 supply derived from weak or diseased plants may 

 stimulate insects to abnormally quick growth and 

 prolific reproduction. This view was supported by the 

 infestation' of thrips on cocoa-trees in the West Indies. 

 Prof. R. D. Watt emphasised the possibility of find- 

 ing strains of cultivated plants immune from insect 

 attack, analogous to those now well known in certain 

 cases as immune from fungus pests. Mr. C. C. Gowdev 

 (Uganda) considered good cultural methods as of great 

 importance in maintaining the resistant conditions. 



A cognate subject, " Artificial versus Natural 

 Methods of Control of Insect Pests," occupied the 

 conference on Wednesday morning. June g. when Prof. 

 R. Newstead presided. Mr. F. W. Urich (Trinidad) 

 opened the discussion with an account of various 

 measures adopted in the West Indies, of which the 

 distribution by means of spraying machines of fungus 

 spores for the destruction of cercopids on sugar-cane 

 was the most remarkable. Dr. Tillyard regarded 

 spraying with insecticides as an imperfect palliative, 

 and looked hopefully for results in poisoning aphids 

 and scale-insects from the inoculation of trees with 

 such substances as copper sulphate. Mr. F. Balfour 

 Browne uttered a warning against the possible danger 

 of introducing parasitic insects- into new countries in 

 order that thev may prey upon previously introduced 

 plant-feeding injects, but Prof. H. Maxwell Lefrov 

 and Dr. .A. D. Imms regarded any danger from this 

 now-established practice as remote. 



Several interesting papers on more special subjects 

 were read. On the afternoon of Mondav, June 7, Mr. 

 G. E. Bodkin p-ave his *>xoerience of the insect pests 

 of British Guiana, and dwelt on the difficulty of con- 



NO. 2642, VOL. 105] 



trolling sugar-cane insects because of their habits of 

 migration. On the same occasion Mr. F. W. Urich: 

 described the insect pests of Trinidad, and Mr. H. .\. 

 Ballou contributed a general review of conditions ia 

 the West Indies. On the afternoon of June 9 Dr. 

 MacDougall lectured on "Insects in Relation to 

 Afforestation," with lantern illustrations, pointing out 

 the bearing of the feeding habits of common British 

 timber- and bark-beetles upon practical questions of 

 forest management. A discussion involving the uni- 

 formity of habit among insects of the same species 

 in all parts of its range was carried on bv Mr. C. F. C. 

 Beeson (India) and Dr. xMunro (Board 'of Forestry); 

 the latter expressed regret that the Scottish and 

 English Scolytidae follow the rules laid down in the 

 classical German text-books of forest entomologv. 

 Mr. F. .A. Stpckdale (Ceylon) followed with an account 

 of the insect pests of tea in that island. On the after- 

 noon of Wednesday, June 2, when Sir David Prairi 

 took the chair, Mr. H. H. Ballou read a paper on 

 "Cotton Pests," dwelling particularly on the boll 

 weevil and the pink boll worm, the latter of which 

 caused a loss of io,ooo,oooZ. in Egypt in the vear 19 17. 

 Cotton insects are controlled by destroying at the end 

 of the season all material in the field in which the 

 species might survive until the next season. Mr. 

 H. H. King described the organisation of entomo- 

 logical work in the .Anglo-Egyptian Sudan, and stated 

 that nine field laboratories under the charge of trained 

 entomologists would be necessary for the proper 

 working of the area. 



Of the special questions discussed the most note- 

 worthy was the tsetse-fly problem, considered at the 

 meeting on Saturday morning, June 5, appropriately 

 presided over by Sir David Bruce. Several entomo- 

 logists from Africa spoke, including Messrs. R. W. 

 Jack (South Rhodesia), Dr. A. May (North Rhodesia), 

 and Mr. LI. Lloyd and Dr. G. D. H, Carpenter 

 (Uganda). .An experiment as to the efl'ect on the fly 

 of the clearance of "big gaine " from a district in 

 Rhodesia is now being tried. The opinion was ex- 

 pressed that the result of this will be disappointing, 

 as mammalian blood forms, as a rule, onlv a small 

 proportion of the food-supply of Glossina. Dr. Car- 

 penter informed the meeting of the success which had 

 followed the erection of inclined screens, under which 

 hundreds of puparia are found ; this means of control 

 was suggested by an observation of the large number 

 of puparia present in the shelter of a blown-down tree. 



The conference concluded on Friday, June 11, with 

 a business meeting, at which several resolutions were 

 passed; these may be briefly summarised, (i) .A con- 

 ference should be held in London every five years. 

 (2) The Imperial Bureau of Entomology should be 

 established permanently; the cessation or curtailment 

 of its work would be deplorable. (3) The Governments 

 contributing to the expenses of the Bureau should be 

 urged to guarantee their contributions. (4) The funds 

 at present contributed for the upkeep of the Bureau 

 are inadequate ; they should be increased so as to pro- 

 vide an income of at least 13,000/. a year. (5) The 

 Colonial Secretary should be requested to establish a 

 provident fund for the Bureau staff. (6) The director 

 and committee of the Bureau should have full power 

 to exercise their discretion as to the scope and contents 

 of the publications and the expenditure involved. 

 (7) The director should encourage members of the 

 staff to pay attention to particular groups of insects, 

 especiallv those for the identification of which no 

 specialist is available. (8) The provision of an 

 adequate number of trained men to carry into effect 

 existing plant-import legislation is of more irrimediate 

 imoortance than the revision or extension of such 

 legislation. 



