145 



after emergence from the pupa. Fertilisation and a blood meal precedes oviposition, 

 and fertilisation preceded the blood meal. Eggs were laid on the sixth or seventh 

 day: After this they regularly fed once, soon after each batch of eggs was laid. 

 Three or four days elapsed between each act of oviposition ; . egg-laying was con- 

 tinued throughout life; the maximum length of life of the males being 28 days, 

 that of females 62. BACOT (1916) states that a female of S. fasciata, which had 

 subsisted on honey and white of egg 56 days without egg-laying, was given three 

 blood-meals; fertile eggs were deposited four days after the first blood meal. Be- 

 sides he remarks that all experiments to induce oviposition in the absence of a 

 blood meal met with negative results in this species. 



Undoubtedly a generalisation with regard to the significance of a blood meal 

 for the ripening of the eggs in the mosquitoes is by no means allowable; every 

 thing seems to point to the fact that the species differ very much from each other, 

 and that there is a regular transition from species which are exclusively vegetable 

 feeders to such to which a blood meal is, if not a necessity, at all events the 

 most natural form of nutriment. 



It is a very remarkable thing that we know species which, in a vast part of 

 their area belong to the most troublesome blood suckers, and in others never seem 

 to suck blood. This seems to be the case with C. territans, which according to 

 SMITH and FELT (1904 p. 309) is extremely annoying in North America, whereas 

 in Europe - - if the determinations are correct - - it is said never to sting man. 

 This has been pointed out by SCHNEIDER (1914 p. 46), ECKSTEIN (1919 p. 64), PRELL 

 (1919 p. 63). 



In our own fauna, too, we possess species which seem never to use blood as 

 nourishment, others which do not suck from man; further, species which seem only 

 rarely and under special conditions to sting man, and lastly, species which seem 

 ready to sting almost at all times. To the first belongs one of our largest species: 

 Culicella morsitans, a species of wide distribution, but according to many authors 

 (THEOBALD, SCHNEIDER 1914 p. 43); never acting as blood suckers. I have hatched 

 this species in many thousands at my laboratory, I have been sitting in the very 

 same dried up ponds over which the females were flying and probably egglaying, 

 and I have caught them in the evenings when they came through the open windows 

 lacing the lake; moreover I have never found females, whose stomachs were red 

 and distended by blood. 



For a long time I thought that this was also the case with T. annulata; I 

 have had the mosquitoes in hundreds in my hatching cages, have very often visit- 

 ed the ponds where the larvae w r ere hatched, and in September gathered plenty of 

 them behind the shutters of the laboratory; further, numerous females on the walls 

 over the cisterns in which they w r ere hatched; nevertheless I have never seen a 

 female gorged with blood, and I have never myself been bitten. FICALBI (1897) 

 has arrived at quite the same result with regard to Italy and so has SCHNEIDER 

 (1914 p. 43) with regard to the environment of Bonn. THEOBALD quotes an observa- 



U. K. I). Vielensk. Selsk Skr., naturvidensk. og mathem. A til. 8, Rrekkc, VII. 1. jg 



