10

hind wings are reduced. but in all others the difYe1eiice depends on the development of the flight-musculature. Flightless forms arc generally less pigmented, have soft, un- pigmented phragmata and the flight-musculature reniaiiis i n the newly-moulted COII-

dition. The two forms are identical a t the final moult and the differences appcwr during later growth.

Flight-muscle development in the small number of species examined is apparently in response to environmental conditions during the late larval or early adult period. At present experiments have oiily attempted to change the musculature from the flight- less to the normal condition. This change is readily achieved by culturing late larvae at temperatures above 20" C. In Xi,qara lateralis the musculature of imagos already laying eggs may develop from the flightless condition in response to changing habitat conditions. A similar change can be brought about in the laboratory by partial star- vation. Analysis of field populations in relation to temperature, habitat stability and general favourability lends support to the thesis of environmental control.

NOTICES The next meeting will be held on Wednesday, 5th Julze, 1963. (1) Dr. L. Bailey-Insect viruses. (2) Dr. N. W. Hussey-The ecology of mushroom-infesting Phoridae (Diptere).

Library The Council of the Society give notice that after April the Society's library will

no longer be open on the third Saturday of the month. The library will continue to be open from 9.30 a.m. to 5.0 p.m. from Monday to Friday, and until the close of the meeting on meeting days. Books may be borrowed by post.

~~

PROCEEDINGS OF THE ORDINARY MEETING HELD ON 3RD APRIL, 1963 Professor V. B. WIGGLESWORTH, C.B.E., P.R.S., President, in the Chair

Present, 72 Fellows and 12 Visitors The minutes of the Ordinary Meeting held on 6th March were confirmed and signed

by the President. The names of the following candidates for election were read for the first time:

Mr. Hirisave Ramarao Gundurao ; Mr. Syed Masood Hasan ; Mr. David Hollis, B.Sc. ; Mr. Peter Joseph Knight ; Mr. Humayun Murad ; Mr. Barry Wright.

Mr. Michael Edward Archer, B.Sc. ; Mr. Walter Vego Baker ; Mr. Michael Henry Hansel1 ; Dr. Mahrus Saleh Hassan ; Mr. Donald Lewis Hope ; Professor Sergius Gregory Kiriakoff, D.Sc., M.A. ; Mr. Peter Alexander Maddison ; Mr. Albert Ukuaghegbele Oboite ; Mr. Laurence Roy Rickman ; Mr. George H. L. Rothschild ; Mr. Clement Singleton ; Mr. Abraham Benedict Soans, M.A. ; Mr. Eric Soothill ; Mr. Charles P. Taylor ; Mr. Reginald Peter Whitehead.

The President announced that the following had been elected Honorary Fellows of the Society :

Captain H. S. Bushell, O.B.E., Ravensholt, Harrow-on-the-Hill, Middlesex. Sir Rickard Christophers, C.I.E., O.B.E., I.M.S., F.R.S., 186, Huntingdon Road,

Cambridge. The Secretary read the names of the following newly elected Fellows of the Society :

Mr. John Henry Ardley, B.Sc., 14, Clarinda Street, Hornsby Heights, N.S.W., Aus- tralia ; Dr. Sven Jorgen Rolf Birket-Smith, M.Sc., Ph.D., University College, P.O. Box 399, Addis Ababa, Ethiopia ; Mr. Ramchandra Nilkantha Ghode, B.Sc., Ll.B., Anaud Kunj Building, Rukharnini Nagar, Amravati, Maharastra State, India ; Mr. Ian Nevill Healey, Department of Zoology, University College of Swansea, Singleton Park, Swansea, Glam. ; Mr. Michael David Richard Jones, M.A., 5, Marlborough Crescent, Bedford Park, London, W.4 ; Mr. Douglas Herbert Mallinson, Walnut Lodge, Kelvedon, Essex; Mr. Govind Pailoor, B.Sc., Mangala Farms, P.O. Chokkadi (S.K.), Mysore

For the second time (taken as read) :

State, India ; Professor Frank Nelson I7ourig. Departmeiii of Zoology. Indiana ITniver- sity, Bloomington, Iiididiia, LJ.8.A.

Thanks were voted to doiiors of gifts to the Library since the last meeting. Mr. M. D. R. Jones a i d Mr. I-l. A . Mi signed the O\dip:ttioii Book .~nd were admitted

Fellows of the Society.

Dr. A. M. Easton exhibited three imagos and one living prepupa of Chrysolampus thenae (Walker) (Hymenoptera : Perilampidae) reared from Meligethes pedicularius (Gyllenhal). Mature host larvae collected from Stachys o$icinalis (L.) Trev. from Flint- shire and Denbighshire were allowed to enter soil in a tube. Some of the resultant cells were visible against the glass and after several days a few of the larvae, having failed to pupate, were noted to harbour a single minute ectoparasite lying transversely across their ventral surface. These grew extremely rapidly, and, when the host was consumed, entered upon a winter diapause. Of the two batches of the host, five out of nineteen, and four out of twenty-five, respectively, were infested. Other Perilampidae are known to start as a planidium which actively seeks out its host.

A short discussion followed in which Dr. Easton said, in reply to an enquiry from the President, that he hoped to ascertain during the coming year the stage a t which the insect found the host,

Mr. G. J. Kerrich commented that the systematic position of the genus Chrysolampus had been a matter of considerable controversy. It belonged to a very distinct sub- family of the Perilampidae and nothing was known of its biology. It was rarely found in this country and there was only one other record of the genus, since the days of Westwood and Walker.

Dr. Easton said, in reply to an enquiry by Mr. W. B. Broughton, that he found only one of these parasites on each Meligethes larva.

Professor 0. W. Richards said that the life history described by Dr. Easton was so very different from that of Perilampus, which had been extensively studied in America, that there might be grounds for wondering whether it did in fact belong to the same family.

Dr. J. D. Gillett gave a talk on mosquitoes and virus diseases of man, an abstract of which appeared on page 5.

The President opened the discussion by asking whether any polio-type diseases were produced by infection with any of the mosquito-borne viruses. Dr. Gillett replied that, although western equine encephalitis in man was a t one time diagnosed as polio, and probably other mosquito transmitted encephalitides have from time to time also been so diagnosed, the mosquito-borne viruses are distinct from the polio-viruses.

Dr. C. R. Ribbands asked how the virus was isolated from the mosquito, how it was then recognised and how it was distributed in the mosquito. Dr. Gillett replied that isolation was usually carried out by inoculating triturated mosquitoes into the brains of infant mice. Identification was obtained by neutralisation tests with known anti- sera. Viruses have been found widely distributed in the mosquito, including the legs and antennae. Some strains, however, fail to reach the salivary glands, and are not transmitted by bite even when the concentration in other parts of the mosquito is high.

Dr. Gillett pointed out that the strains he had in mind were laboratory strains. Nevertheless, failure to be transmitted by bite occurs with some wild viruses, but propagation goes on through alternative species of mosquitoes.

Dr. C. G. Johnson asked if there were any viruses that were mechanically trans- mitted in the manner of some plant viruses. Dr. Gillett replied that the transmission of myxomatosis virus in Australia was a classic example. In the viruses that had been discussed, however, transmission was biological, and multiplication in the mosquito may be a millionfold. He continued, in reply to an enquiry by Dr. Ribbands, that there was no evidence that these viruses had any effect on the insect host.

Dr. Johnson enquired further about the distribution of the virus in the mosquito. Dr. Gillett stated that no virus of this type had ever been found within the eggs.

I n reply to an enquiry as to why o’nyong-nyong spread in one particular direction,

Recently five adults were obtained.

Mr. W. B. Broughton wondered how such strains managed to propagate.

12

Dr. Gillett agreed that it followed the distribution of dnophe2es f icmstcrs, but that movement of people helped it to bridge gaps between one fisnestiis population and another. There were over a million mseq in the f u n ~ s t u s itreas of IJganda, followed by qmradic outbreaks around the ports of Lake Victoria and along the railway line below certain altitudes.

Dr Gillett replied that infection of mosquitoes by man usually occurred during the first few days of illness, when the virus level in the peripheral blood was high.

Dr. J. A. Reid asked the present position about the most puzzling feature of these virus diseases, namely, what happened to the virus in the winter in temperate regions. Dr. Gillett replied that this problem was still largely unsolved. It could not be wholly explained by migratory birds, but i t was known that overwintering mosquitoes could harbour certain viruses until the following spring.

In thanking Dr. Gillett for his lucid account of this very complicated problem, the President observed that the phenomenon of diseases being maintained in wild animals and occasionally spreading to man was frequently encountered in tropical medicine and might well give rise to a few reservations about the present day drive to conserve wild animals.

In the history of medicine there were frequent records of mysterious and often fatal diseases which, although described in great detail, could not be diagnosed and it was a fact that even today a new virus infection of devastating epidemic proportions could arise.

Professor 0. W. Richards asked at what point human beings were infective.

Dr. Fse Hall (a visitor) showed four films on insect and arachnid behaviour made by the Granada Zoo Television and Film Unit. h i account of these films appeared on pages 5 and 6.

Dr. Hall gave a commentary on the films while they were being shown. In answering a number of points that were raised afterwards, Dr. Hall said that

insects were easier to film than many other animals. They were not so adversely affected by heat, and i t was possible to use containers that restricted movement.

In reply to an enquiry from Dr. Hall, the Secretary said that the white markings on the head and antennae of Gomphocerippus rufus were unusual in grasshoppers, and that the visual component of the courtship behaviour was exceptionally large.

The President thanked Dr. Hall for giving the Society the opportunity of seeing these films, which enabled the behaviour of the insects and arachnids to be observed with greater clarity than was possible in nature.

DAVID R. RAGGE, Hoizorary Secretary.

ADDITIONS TO THE LIBRARY Presented

Centre National de la Recherche Scientifique. Physiologie, comportement et icologie des Acridiens en rapport avec la phase. Paris du 9 au 13 Avril, 1962 . . . par M. F. 0. Albrecht. Paris, 1962. [Colloques Internationaux du Centre Natiofial de la Recherche Scient$que No. 114.1 [The Publishers.]

Grinfeld, E. K. The rise of antophily in insects. 8vo. Leningrad : A. A. Khdanov State University, 1962. [The Publishers.]

O’Farrell, A. F. L. The clock i n the cockroach. 8170. Armidale, New South Wales: The University of New England, 1960.

Sweeney, R. C. H. Red locust (Nomadacris septemfasciata) in Nyasaland. 8vo. Zomba, Nyasaland : Information Service of the Ministry of Natural Resources and Surveys, 1962. [Bulletin No. 2.1 [The Author.]

(Actes du Colloque International, organis6 8vo.

[The Author.]

PRINTED BY ADLARD AND SON, LIMITED, BARTHOLOMEW PRESS, DORKINO.