193 



Detailed information is given as to the breeding places found in 

 this survey, and the distribution of Anophehnes in Bavaria is dealt 

 with very fully. There is a general distribution of Anophehnes, which 

 were absent only in a very few localities and then only owing to the 

 lack of suitable breeding places. In the Bavarian Alps the altitude 

 range extends up to about 3,300 ft. 



The past distribution of malaria in Bavaria is described ; the 

 possibility of an endemic spread of the disease is considered remote. 

 The almost complete disappearance of the disease in the last 50 years is 

 due to improved hygienic conditions and to the greater dryness of 

 the country, the level of the subsoil water having fallen owing to 

 drainage, etc. 



KoNsuLOFF (S). Die Bekampfung der Malariamiicken in den Reis- 

 feldern. [The Control of Malaria Mosquitos in Rice Fields.] — 

 Zeitschr. angew. Ent., Berlin, viii, no. 2, May 1922, pp. 283-294. 



The economic value of rice fields, which produce a world crop of 

 120 million tons, renders measures against the Anopheline larvae that 

 breed profusely in them of great importance. In Europe rice is 

 grown in Spain, Italy, Macedonia and South Bulgaria, and for lack 

 of a suitable method of dealing with the mosquitos the plan has been 

 followed of prohibiting rice cultivation within a certain distance of 

 towns and villages. 



Attempts to check the larvae by means of fish and other natural 

 enemies have had no real success. The only practical measure consists 

 in allowing the fields to dry up some few times during the rice- 

 growing season. Celli and Casagrandi found that larvae of Culex could 

 live on damp ground and that pupae developed on dry sand, and 

 this caused Grassi to abandon the idea of intermittent irrigation. 

 The author, however, points out that no examples of Anopheles were 

 used in these experiments, which were made in the laboratory. 

 Finding that the resistance of these two genera differs, and that the 

 resistance of a larva varies with its stage of development, he reinvesti- 

 gated the question. An examination of the resistance of the larvae 

 and pupae of Anopheles maculipennis, Meig., to heat, desiccation and 

 asphyxiation gave the following results. 



Larvae and pupae freshly collected in the open were placed in a 

 thermostat at 32° C. [89-6° F.]. After 12 hours, larvae of all three 

 stages were alive, some of the pupae had yielded adults and others 

 had died ; this applied to specimens in water. On damp earth a few 

 only of the first and second stage larvae were dead, but all the third 

 stage larvae were dead, together with some of the pupae, while the 

 remainder of the latter had yielded adults. In water at 35° C. [95° F.] 

 after 24 hours all the larvae of the first and second stages were dead, 

 while of the pupae some were dead, some were alive and some had 

 yielded adults. On damp earth all the larvae (except two of the 

 second stage) were dead, and of the pupae some had yielded adults, 

 others were dead and one was alive. At 37° C. [98-6° F.] all the 

 larvae and pupae, except a few of the latter that had yielded adults, 

 were dead after 24 hours in water. All died after six hours on damp 

 earth. 



The joint action of incomplete desiccation and direct sunlight was 

 tested in the open air at Sofia. The experiments were made in August, 



