80 



of a mynah and of a kite. Phlehotomus argentipes was observed to 

 emerge from nest materials in the laboratory, and though no larvae 

 were found, several empty pupal cases were discovered. These 

 midges were also observed in large numbers in the cages of ostriches 

 and other birds in the Victoria Garden at Bombay. Cimex hemipiera 

 {rotitndatiis) in all stages, and pupae of Hippobosca maculata, were 

 also found in a mynah's nest, and a Muscid was found breeding in the 

 nest of another bird. 



Experiments on the effect of soluble and insoluble salts and poisons 

 on mosquito larvae and pupae seem to confirm the conclusion that 

 soluble substances operate chiefly cutaneously and insoluble ones 

 orally. A series of experiments were carried out on the deterrent 

 effects of many chemicals on Dacus (Choetodacus) zonatus with a 

 view to finding out the chemotactic reactions of fruit-flies and of 

 mosquitos. The numbers of flies that came to the various repellents 

 were as follows : — Cinnamic aldehyde, ; turpentine, 38 ; camphor, 

 17 ; naphthaline, 22 ; kerosene, 12 ; benzine, 27 ; acetic acid, 19 ; 

 carbolic acid, ; oxalic acid, 1 2 ; hydrochloric acid, 1 1 ; sulphuric 

 acid, 3 ; mercuric chloride, ; soap, 13 ; formalin, 29 ; amyl acetate, 

 78 ; methyl eugenol, 33. 



In attempting to discover the role of blood in ovulation in mosquitos, 

 eggs were obtained by feeding with peptone and milk, without any 

 meal of blood, from Stegomyia albopicta (scutellaris) and, in one instance, 

 from 5. vittata {sugens). Eggs were obtained in two out of four experi- 

 ments with shed goat's blood. Mosquitos enclosed with tender plants 

 died within four days without ovipositing. Saccharine and glycerine 

 in various strengths were offered to mosquitos, 'but they refused to 

 feed on these substances. 



Experiments with bed-bugs [Cimex lectidariiis] at varying tempera- 

 tures showed that a two-minutes exposure to a temperature of 126°F. 

 is sufficient to kill them. 



Tests with various repellent preparations against Armigeres 

 ohturbans were made, and the results are s'hown in a list giving the 

 average efficacy of each. It seems hardly possible to produce a pre- 

 paration that will remain fully effective for three hours. A list is 

 given of substances that remain effective for over nine minutes. Tests 

 of the repellent properties of about 40 substances at distances of three to 

 four inches were made. These led to the conclusion that the factors 

 concerned with distance repulsion and contact repulsion are probably 

 not identical. Neither method of repulsion is apparently proportional 

 to the poisonous effect on the mosquito of the vapour of the substance 

 used. Mosquitos probably cannot be kept at a distance from the 

 body by any practically applicable chemical repellent for any length 

 of time. A list of the chemicals tried is given in the order of their 

 merit, creosote, naphthaline and wood oil standing first. 



M.vcKiNxoN (E.). The Relation of Insects to the Dissemination of 

 Diseases. — Science & Iiidiistrv, Melbourne, ii, no. 11, November 

 1920, pp. 652-658. [Received 2nd March 1921 .] 



The relation of certain insects to the dissemination of diseases has 

 now become an accepted fact. The various ways in which micro- 

 organisms may be transmitted by insects, whether actively carried, 

 mechanically carried, or by means of indirect association, are briefly 

 described with examples. 



