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Anopheles maculipennis is the commonest Anopheline in Albania. 

 Warm animal quarters, especially low goat sheds, are preferred as 

 shelters to human dwellings, which are usually colder. The species 

 of animal seems of less importance than the construction and temper- 

 ature of its dwelling. Goat sheds built of wood and straw harbour 

 thousands of mosquitos, whereas those constructed of stone only 

 contain a few. All the specimens found in winter were females, 

 though a few males, usually 2 per cent., may occur in October. The 

 percentage of males is subject to daily variations that need biological 

 investigation. The highest (37 per cent.) occurs during the first 

 summer flight ; in August the average is 20-25 per cent., and this 

 figure falls to 10-12 per cent, in September. Of the hibernating 

 females a very large number perish, and the mortality may amount 

 to nine-tenths of those in stone-built houses. 



In one instance an epidemic was observed, evidently due to an 

 infectious disease ; a fungus, similar to Empusa imiscae, and a micro- 

 organism. Bacillus subtilis, were both observed on this occasion. 



Measures against the adults are the most important form of work in 

 the cold season, and the best time for them is in the autumn. They 

 were carried out by burning the mosquitos off with a blow lamp, by 

 sulphur fumigation (2 gm. per cu. metre of space), which was effective 

 only in the better built houses, and by spraying with a solution of 

 formaldehyde soap (2 per cent, formalin and | per cent. soap). In 

 the last-named measure, soap of a good quality is essential if the 

 formalin is to prove effective. Cresols have a marked killing action 

 on mosquitos, and both lysol and lysolcresol contain enough soap 

 to be very efhcient. These solutions were not only sprayed but were 

 poured into cracks in floors. They are better than formaldehyde 

 for use in stables owing to the absence of pungent vapour. 



From May to June the hibernated female flies in the open, deposits 

 250-300 eggs, and dies — usually on the day following oviposition. In 

 August only 150-200 eggs were laid, and the females did not die. 

 Specimens captured in September and October laid only 50-70 eggs, 

 and also remained alive. 



The eggs laid in late autumn are darker in colour, owing to a thicker 

 chitinous shell, than those laid in summer ; they are laid singly and 

 often sink in water. In the incubator, at a temperature of 37° C. 

 [98-6° F.] they required 8-10 days to hatch, whereas summer eggs 

 do so in 2-3 days. They appear to be true winter eggs adapted for 

 hibernation in the open. From muddy reeds placed in water in a 

 warm room newly hatched Anopheline larvae were obtained in about 

 three weeks, so that it is certain that the dry mud protects the eggs 

 against cold and that the floods due to the spring thaw cause hatching. 

 Such eggs produce larvae at an earlier date than that on which the 

 winter adults appear in the open. Hibernating larvae were never 

 found. 



Experiments show that when exposed for a long time to a temper- 

 ature at freezing point the larvae become motionless and sink to the 

 bottom of the water. In nature this must prevent them from being 

 frozen in ice, and results in their reaching the lower, warm layers of 

 water. All the experimental larvae died after six hours when frozen 

 in ice. Where the temperature varied from —2° to 10° C. [28-4° 

 to 50° F.] and a coat of ice was formed for only eight hours daih^ the 

 larvae began to die only after 2^ months. Feeding did not increase 

 their size, nor did they pupate, but when placed in a temperature 

 of 22° C. [71-6° F.] they pupated within 48 hours and became adult 



(6301) H 



