a 



151 



with a salt content between 0-4 and 12-5 per miUe, in one instance 

 larvae being found in a pool with a salt content of as much as 21 -7 per 

 mille owing to evaporation. It is necessary either to shorten the period 

 between clearing and reclaiming, or to arrange for a free communication 

 with the sea in order to prevent the salt content being decreased by 

 rain water A. umbrosus was caught once only, though the larvae 

 were not difficult to find. It is doubtful whether this species is a 

 malaria carrier in Sumatra. 



The endemic malaria was characterised by the frequent occurrence 

 of quartan together with mahgnant tertian. The latter was of a 

 very severe character, a fact that the authors have noticed m all 

 epidemics due to A . ktdlowi, which was the only earner present. 



A comparison of the infection index figures of mosquitos captured in 

 dwellings and of those from adjacent buffalo sheds, which are provided 

 with mosquito traps or themselves act as traps, shows that the former 

 are considerably higher and points to a tendency of A. ludlowi to 

 stay at a place that has been once chosen. The location of buffalo 

 trap-sheds appears to be of great importance as regards results. A 

 position on open ground— at a distance of 10-20 yards from the 

 dwellings— instead of among trees seems preferable, but actual tests 

 should be made until the best position is ascertained. Buffalo sheds 

 built underneath dwellings required a few days ^o become attractive 

 to mosquitos The experiments point to buffalo sheds being— under 

 favourable conditions— extraordinarily attractive to A. ludlowi ^nd 

 other mosquitos. One buffalo may divert most of the A . ludlowt from 

 the dwellings of 100 people. Furthermore, a buffalo shed is a rehable 

 indicator of the changes in the Anopheline fauna in a certain area. 



Jaarverslag der Malariacommissie voor NoordhoUand over 1921. 



[Annual Report for 1921 of the Malaria Committee for the Province 

 of North Holland.]— Reprint, dated May 1922, from Verslagen 

 en Meded. V olksgezondheid [sine loco], 26 pp., 1 map, 2 figs. 



Near Amsterdam the first Anopheline larvae, apparently those of 

 Anopheles bifurcatus, were seen on 16th March. The first find of 

 larvae of A. maculipennis was made on 29th April, and the first males 

 on 16th May. These dates were earlier than in 1920 [R.A .E., B, x, 19]. 



The drying up of many canals owing to the abnormal summer 

 drought wa'^ unfavourable to Anophelines. The admission of sea-water 

 increased the salt content of inland waters, but the gradual change 

 seems to have had fit tie effect on the larvae. The mosquitos were 

 active for a somewhat longer period owing to the warm autum.n. 



A general campaign against the larvae is impracticable in the 

 reclaimed lands. By spraying ponds with 30-40 gm. of creolin per 

 square metre (about 1-H oz. per 11 sq. ft.) nearly all animal life 

 was killed, but four weeks later many larvae and some pupae occurred 

 in them. ' A spray of finely divided hquid paraffin also killed the 



Work against the adult Anophelines indoors was done only in winter, 

 being stopped in March. Spraying with a 3 per cent, solution of lysol 

 was the best measure for large scale work. The adults prefer stables 

 and pigsties to cowsheds. Rabbit burrows in the dunes and under- 

 ground^ passages in fortifications were not infested, though the latter 

 harboured many Cw/ea-. 



A table, covering two years from January 1920 to December 1921, 

 shows the'percentage of infection in Anophelines captured in dwellings 



N 2 



(6975) 



