161 



very little, satisfying their respiratory claims through the air dissolved in the water. 

 - In spring the larvae appear again in the water rim, and in the detritus washed 

 ashore in the spring months the pupae appear together with those of Dixa, Cera- 

 topogon and many pupae of Chironomidcv . ECKSTEIN (1918 p. .530) has arrived at 

 quite similar results. MARTINI (1920 p. 63) indicates that A. bifurcatus most probably 

 quite like the Aedini hibernate as eggs which should then be hatched very early 

 at low temperatures. I do not think this supposition is correct. It seems as if 

 A. bifurcatus, both as imago and as larva, is more accustomed to low tempera- 

 tures than A. maculipennis, occurring partly as larva in cold, slow running moun- 

 tain streams and as imago higher up in the mountains. (See f. i. PRELL 1917 

 p. 243; MARTINI 1920 p. 67). How many generations are produced in the course of 

 a year I do not know, but I should think not more than two. - The one is laid 

 as egg in Sept., winters as larva, the larva life lasting about eight months, and is 

 imago in May; the other is laid as egg in May June; the larva life lasting not 

 more than one or two months; and the imagines appear in mid-summer. 



As far as we know there are only few of the Anophelince which hibernate as 

 larvae (see GRIFFITS 1918 p. 1996. LACAZE 1918 p. 729). LEGER 1917. NUTTALL and 

 SHIPLEY 1901 p. 452). 



A. maculipennis. 



When I began my investigations on the Danish Culicidce I supposed that A. 

 maculipennis was one of our most common mosquitoes; STAEGER (1838 p. 552) 

 writes "common from April to September; the female common on the windows of 

 houses". To my great astonishment I never saw A. maculipennis in Nature. The 

 single Anopheles species which for years I could find was always A. bifurcatus; in 

 houses I certainly saw a few but never any great number. 



It is a well-known fact that in our country we have formerly had a very 

 serious malaria epidemic; we are therefore forced to suppose that at that time, not 

 a century ago, swarms of Anophelines must have been hatched every year. As for 

 the whole of Europe A. maculipennis is nowadays undoubtedly the chief malaria 

 carrier and as North of the Alps we have never found more than the three 

 Anop/ie/es-species mentioned in this work, and the significance of the two others as 

 malaria carriers, especially of A. niyripes, has always been but slight, we are almost 

 forced to suppose that it really was A. maculipennis which was the malaria carrier 

 a century ago; as my investigations however showed that A. maculipennis nowa- 

 days seemed to be an extremely rare mosquito, it really seemed that all those 

 naturalists and physicians were right, who maintained that one of the main causes 

 of the disappearance of malaria from more northern latitudes was really the dis- 

 appearance of A. maculipennis. 



One day in 1918 I happened to enter a cowhouse, lying near my laboratory 

 at Tjustrup. To my great astonishment I then saw A. maculipennis in incredible 

 numbers hanging down from the ceiling of the stable and especially from all the 



D. K. D. Vidensk. Seisk. Skr., naturvidensk. og mathem. Afd. 8. Rjekke, VII, 1. 21 



