158 



and simple; the outer anterior clypeal hairs too; the equipment of hairs on the 

 thorax and abdomen is much richer and the colour of the body is remarkably red- 

 dish brown; the whole larva has, as LANG (1920 p. 78) writes, a more stumpy look 

 than that of A. maculipenms and A. bifurcatus. I observed the tree-hole almost every 

 day till 15. August, the hole being only a few hundred yards from my summer 

 laboratory; there were about a hundred larvae in the hole; they pupated in the first 

 part of August and the imagines A. plumbeus were hatched before my departure; all the 

 larvae I saw in the tree-hole were fullgrown ; that a new generation of larvae should 

 appear in autumn is highly improbable. The larvae were always lying at the surface 

 but at the slightest shaking of the earth round the tree stump they darted away 

 from the surface and disappeared at the bottom of the dark brown water. 



ECKSTEIN (1919 3 p. 532) supposes that the species hibernates as imago. Besides 

 I refer to EYSELL (1912 p. 421). The species is often but not exclusively found in 

 tree holes also in peat holes (BLANCHARD 1918, MARTINI 1915 p. 585, THEOBALD 

 (1910 p. 13), it has been recorded from most European countries lastly from France 

 (CORDIER 1918 p. 726; LANGERON 1918 p. 728). Its significance as Malaria carrier is 

 very small (BACOT 1918 p. 241); but BLACKLOCK and CARTER (1920 p. 413) have shown 

 that infection really is possible; the peculiar eggs differing from the eggs of other 

 European species in having a ring of floating cells all round have been described 

 by EYSELL (1912 p. 423). 



A. bifurcatus. 



A. bifurcatus is a well-known species recorded from Denmark already by 

 STAEGER (1838 p. 552); it is regarded as rare and this, as far as I can see, is the 

 case with regard, to most of the localities in Central and North Europe. - - In my 

 opinion it is not so with our country; insufficient knowledge of the biology has 

 caused the impression that the species is much rarer than is really the case. 



The first specimens appear in the middle of May; I have not found specimens 

 after the first part of September; I have found the greatest number in June July. 

 A. bifurcatus is mainly an outdoor species, the home of which is dark forests, old 

 gardens, the outskirts of old beeches, especially where these border on lakes. Even 

 if the locality contains numbers of A. bifurcatus during the twenty hours of the day 

 and night we shall hardly see anything of it; in a great many localities in Den- 

 mark I and some persons with whom I have been acquainted have made quite 

 the same observations. 



Until a little after sunset we have all been tormented by the different Ochlerotatus 

 species; then when it is so dark that it is difficult to distinguish the different spe- 

 cies from each other, mosquitoes of very slender form and with very long legs 

 appear; it is A. bifurcatus - as far as we hitherto know in our country never 

 A. maculipennis - which now displaces the Ochlerotatus species; - their flight 

 is quite silent, and I have never had the slightest sensation of the mosquito 

 when it alighted upon my hand; the sting is very painful. Different people in the 



