I04 



NA TURE 



\ynne 7, 1877 



In trying to throw light upon an obscure explanation in 

 our lexl-book, my brain took fire, I plunged with re- 

 qiiickcned zeal into a subject which I had for years 

 abandoned, and found food for thoughts which have 

 engaged my attention for a considerable time past, and 

 will probably occupy all my powers of contemplation 

 advantageously for several months to come. 



067? INSECT FOES 



A N important conference was held at the Society of 

 -^*- Arts on Tuesday afternoon on the subject of insects 

 injurious to agriculture and methods of stamping them 

 out. Its origin was a proposition by Mr. Andrew Murray 

 (who has had the arrangement of the collection of eco- 

 nomic entomology made by the Science and Art Depart- 

 ment), which he laid before the Lord President of the 

 Council. The proposition was printed by order of the 

 president, and copies were sent to the agricultural socie- 

 ties and chambers of agriculture of the country. After 

 the proposition had been before them for two months and 

 there was no indication of any notice being taken of it, it 

 was arranged that a conference of delegates of agricultural 

 societies should be held at the Society of Arts. The Duke 

 of Buccleuch, K.G., took the chair, and there were present 

 representatives of the Scottish, Cheshire, Warwick, Hamp- 

 shire, and Banbury Chambei s of Agriculture ; the Farmers' 

 Club, Dr. Maxwell Masters, representing the president of 

 the Royal Society, Prof. Voelcker (chemist to the Royal 

 Agricultural Society), Mr. Sewell Reed, M.P., &c. The 

 conference v,-as opened by a paper read by Mr. Murray. 



The paper commenced by assuming as an axiom that, 

 besides the occasional great injury done by insects, by 

 which whole districts are ravaged, a continual drain is 

 constantly kept up by thern, which constitutes a very 

 perceptible percentage of deduction from the cultivators' 

 profits ; and, further, that where this loss can be pre- 

 vented at less cost than the loss it occasions, it should be 

 prevented. 



It next maintained that, if we wish to rid a district or a 

 country of an injurious insect, to be effective, any attempt 

 to do so must be simultaneous and combined, for to what 

 purpose would it be if one man cleared his farm if 

 his neighbour did not clear his ; or if the one cleared 

 his one year, and the other clenred his another.' A 

 central authority, therefore, is needed to secure united 

 action. 



It next considered the various ways in which the insects 

 injurious to agriculture might be extirpated. The first, 

 the simplest, the most powerful, and the most erticient of 

 these is county or district rotaiion of cropping. Farmers 

 know well enough the advantage of a rotation of cropping 

 (or its equivalent) on their own farms. By long-continued 

 growth of the s.ame crop on the same land the soil 

 becomes exhausted of some of the elements necessary for 

 the proper development of that kind of crop, and a change 

 of crop brings other elements into use, and relaxes the 

 demand upon those that have been too much drawn 

 upon. 



Exactly the converse of this takes place with regard to 

 certain insects. The great majority of vegetable-feeding 

 insects do not feed on all kinds of plants indiscriminately ; 

 most of them are restricted to one kind of plant, and if by 

 cultivation of that plant its numbers are enormously in- 

 creased, so will naturally be the number of the insects 

 that feed upon it ; while, if we should cease to grow that 

 plant, the number of the insects would correspondingly 

 diminish. Thus, for instance, if a district is almost 

 entirely in pasture, there will be very few wheat-feeding 

 insects in it, but if it is turned into a wheat country they 

 will be myriads. If these numbers reach such a pitch as 

 to deteriorate the crops the remedy is plain. Change 

 the rotation, and grow some other crop instead of wheat. 



Most of the wheat insects are only annuals. If they 

 could be banished for one year they would be banished 

 entirely, or until re-introduced. Now, if there were a 

 controlling authority, wh.at would be easier than to say to 

 the farmers, '' Gentlemen, in the common interest you 

 will substitute barley fur whe.at in your ne.Kt year's rota- 

 tion." The insect, deprived of its proper nidus, must then 

 either lay its eggs in an unsuitable place where they 

 will perish, or have recourse to the pasture fields for 

 Tritiiutit i-i-pcns, or other suitable grasses. By this, of 

 course, the fly would not be exterminated, but its numbers 

 would be so reduced as to render it comparatively harm- 

 less, at all events for a time, v/hen, if it again reappeared 

 in force, the same means of defence would be resorted to. 

 Nay, it might be so arranged that two or more counties 

 might brigade themselves together, so as to establish a 

 permanent see-saw by which they should play into each 

 other's hands. But no single man can carry out such a 

 rotation. He may try it upon his own fields, but they 

 v.-ill be replenished continually from the fields of his 

 neighbours, unices they at the same time are compelled 

 to follow the same rotation. 



Mr. Murray then went over the various other meanj of 

 extirpation — picking and burning infected plants, the 

 collecting caterpillars, poisons, and .local remedies, in 

 relation to which he drew attention to the destruction of 

 what are called ticks and lice upon sheep. Everyone 

 knows how readily such vennin can be communicated by 

 contact or even proximity, and it does seem a very hard 

 case that a man, who has kept his flock clean by taking 

 proper precautions, should be liable to have them infected 

 by a neighbouring neglected flock, by stray sheep, or even 

 by sheep passing along the road. It is said that, catcris 

 paribus, the difference in value between a sheep that has 

 been kept clean for the season and one that has been 

 worried by vermin will be los. If that is so it is a 

 wonder that sheep farmers have not long since clamoured 

 for some supervision. 



At the conclusion of the paper the following resolution 

 was put from the chair and carried :— " That thanks are 

 due to the President and Lords of the Council for having 

 brought the subject of insect damage under the con- 

 sideration of the agricultural bodies o! the kingdom." 



Dr. Maxwell Masters moved the next resolution, and 

 in doing so said he was charged to express the regret of 

 the President of the Royal Society that he was unable to 

 be present. He spoke of the great ignorance throughout 

 the country on the subject of insect damage, and as an 

 indication of the amount of damage done, said that half 

 the time of the Scientific Committee of the Royal Horti- 

 cultural Society was occupied with answering inquiries 

 from all parts as to how to deal with insect foes. The 

 resolution he moved was, — " That much of the loss occa- 

 sioned by insects is preventible, and ought to be pre- 

 vented." This was seconded by Mr. Maclagan. and 

 carried. 



Mr. Mechi then moved — " That it properly belongs to 

 Government to provide the necessary means for protecting 

 cultivators from this loss, as it is only by combined and 

 simultaneous action over considerable districts that it can 

 be effectually done, and Government alone possesses or 

 can obtain the requisite means of enforcing such action." 



Both Mr. Mechi in moving it and Prof. Voelcker in 

 seconding it, spoke of the want of knowledge throughout 

 the country on the subject. Mr. Sewell Reed urged it was 

 not a question for government but fo;' agricultural socie- 

 ties. The resolution was declared carried, though many 

 hands were held up against it. 



The last resolutioa was — "That the President and Lord.s 

 of the Council and the Agricultural Societies of the United 

 Kingdom be informed of the opinion of this Conference, 

 and urged to take the subject at once into their considera- ■ 

 tion, with a view of providing a remedy," which, after a 

 long discussion, was carried. 



