OTAGO INSTITUTE. 



First Meeting : I2th May, 1908. 



The President, Dr. Hocken, in the chair. 



New Members. — The Yen. Archdeacon Gould, Dr. E. Williams, Dr. W. 

 Evans, Dr. Stuart Moore, Messrs. Whitson, Braithwaite, Crosby Smith, and 

 Robert G. Thomson. 



The President announced that Mrs. Hutton (widow of the late Professor 

 Hutton) had presented to the Institute a copy of Professor Hutton's book 

 " The Lesson of Evolution," being the second edition of his work on 

 Lamarckism and Darwinism. 



A vote of thanks was uuaniinoiisly accorded Mi's. Hixtton. 



An engraving of Lamarck, presented to the Institute in return for its subscription 

 to the international fimd for the erection of a statue to the celebrated naturalist, was 

 also received and promptly acknowledged. 



Mr. A. H. Cockayne, of the biological section of the Department of 

 Agriculture, exhibited a breeding-case showing three hundred ladybirds 

 of the genus Rhizohius feeding upon the blight which a few years ago 

 threatened to exterminate the blue-gum from South Canterbury. 



Tnthe course of a few very interesting remarks Mr. Cockayne said that in 1900, in the 

 plantations at Timaru, a strange insect was found to have infested the leaves and branches 

 of the gum-trees. The insect turned out to be an Australian scale insect of the genus 

 Eriococcus, and had in all probability been introduced in the bark of the hardwood timber 

 imported to Timaru from Australia for the harbour-works. Finding the climate of 

 Timaru congenial, in a short time it spread over an area of about 3 square miles. All 

 the young branches of the gum-trees became covered with the scale, and in about eighteen 

 months the trees died. By the end of 1904 a large number of plantations, some of which 

 had been planted fifty years ago, were dying wholesale through the attacks of tliis disease. 

 Spraying was, of course, c{uite out of the cpiestion as a remedy, and the only possible 

 solution of the difficulty was to import the natural ladybird enemies of the scale, which 

 keep it in check in Australia. The biological branch of the Department of Agriculture 

 tried as early as possible to get shipments of the natural enemy, and to establish it at 

 Timaru. The Australian seasons, however, were not at first favourable for collecting 

 these ladybirds, and it was not until the end of 1905 that the first shipment of about 

 two thousand was i-eceived. These were placed in some of the badly affected plantations 

 about Timaru, and there they were left, with the object of seeing whether they would 

 survive the winter. The ladybirds increased rapidly, especially a pure-black one {Rhizo- 

 hius vcnirnlis). So rapidly did this variety increase that next year the Department was 

 able to send consignments to every infected part of Canterbury. Gum-tree planting had 

 been entirely abandoned in the southern part of the province by reason of the ravages 

 of the scale. Thanks, however, to the little black ladybird, all that was now changed, 

 and the plantations which a couple of years ago were considered to be ruined had regained 

 their normal health, and there was every probability that within another year the scale 

 would be absolutely wiped out. This, continued JIi'. Cockayiie, was one of the most 

 interesting experiments in insect-control ever undertaken. Previously the only one noted 

 in text-books was the famous natural enemy of the cottony cushion-scale.^ which did such 

 exceNcut work in the orange-groves of California. 



Dr. P. Marshall exhibited specimens of rocks sent from South Victoria 

 Land by Professor David, of Sydney University, who accompanied Lieuten- 

 ant Shackleton's Antarctic expedition. 



One of these rocks, a volcanic lava, said Dr. iMarshall, was of more particular interest 

 to Dunedin tlian to mo.st cpiarters of the world, because the type was of very rare occur- 



