171 



then T. annulata may be present in relatively large numbers; these large mosqui- 

 toes, which, quite like .4. maculipennis, are almost always blood-filled, resemble 

 Hies and are as sluggish as A. maculipennis. Also Martini (1920 4 p. 13) states that 

 he has rather often found A. bifurcalus in stables. 



19. With regard to the number of generations in our country we only know 

 very little. The last broods of the last summer generation hibernate and most prob- 

 ably die out in June, living about eight months. The summer generation is born 

 in June and produces a series of broods; that these broods again produce a new 

 generation is in my opinion probable, but more than two generations a year I do 

 not suppose will appear. Kilagin (1907 p. 867) has arrived at a similar result with 

 regard to Russia (one generation). Prell (1917 p. 262) seems to be of a similar 

 opinion: he says: "dass die A. maculipennis Larva verhaltnismassig hohere An- 

 spruche an die Temperatur stellt als Culex und daher fur gewohnlich sich wesentlich 

 langsamer entwickelt. Bei einer durchschnittlichen Tp. von 20° C. war eine Zucht 

 allerdings bei schwacher Ernahrung nach 5 Wochen noch nicht fiber das zweite 

 Stadium gekommen". Eckstein ( 1 9 1 9 2 p. 94), Martini (1920! p. 63) indicate 2 — 3 

 generations at Strassbourg and Hamburg. Unquestionably the number of generations 

 in the south is much greater. Grassi (1900 p. 81) found that the development from 

 the moment when the larva left the egg and to the transformation to imago lasted 

 30 days at tp. 20 — 25° C. Twenty days later these flies in turn laid eggs. In the 

 long Italian summer there will certainly be time for a whole series of generations; 

 this has also been stated for England by Nuttall and Shiplky (1902 p. 68) and 

 for Austria by Kerschbaumkr (1901 p. 85). 



If now we will summarise our knowledge with regard to the biology of A. 

 maculipennis in Denmark nowadays, we shall arrive at the following remarkable result. 



A. maculipennis is almost for the whole of its life bound to human 

 habitats; in summer to the stables, in winter to outhouses, only leaving 

 the houses for mating and egg -laying processes. It sucks blood upon 

 the domestic animals, pigs, cattle and horses, not upon man; this is 

 only the case where opportunities to suck blood upon animals are 

 wanting or insufficient; nowadays the females are extremely sluggish, 

 hanging blood-filled, often in incredible numbers, upon the ceiling 

 and walls of the stables. They are hardly ever met with in Nature 

 itself and as a rule they do not fly through the windows into the rooms 

 in the evenings. 



It is a well-known fact that malaria was formerly one of the worst epidemics 

 we have had in this country. Its history here has been treated by C. A. Hansen 

 (1886) and by Goldschmidt (1886 p. 29). With regard to older literature I more 

 especially refer to Cold (1857 p. 109). I shall here by no means enter into detail, 

 but referring the reader to these papers only call attention to the following facts. 



