127 



the life-history of the species in our country as well as elsewhere, it will be appa- 

 rent that this is still quite impossible. According to my experience it is the most 

 troublesome species to study; as far as I can see, here lies a special problem which cannot 

 be solved together with the life-history of all our other mosquitoes. The following remarks 

 may be regarded as points of support for such a future, more thorough, examination. 



In November I have often found the females in numbers in summer houses 

 arbours etc., but during winter they commonly disappear from localities of this 

 nature. The females hibernate in deep sheltered, frost less cellars; hitherto, as far as 

 I know, we have never in winter found the mosquitoes in Nature. As long as the 

 temperature is above zero, the mosquitoes are able to fly when a light is brought 

 near them; they hang down from walls and ceilings often in such huge masses that 

 these are covered with them; the hibernating localities in our houses must always 

 be dark, rather moist; and without any draught at all; it is not necessary that they 

 are frostless; if the temperature falls below y zero, they fly deeper into the cellars; 

 during severe winters they often retreat to places of such a sheltered nature that it 

 is difficult to find them. 



Now and then they may also be found in localities where we should not ex- 

 pect to find them. In an old, almost put down farm of which only the walls and 

 the chimney were left, in Dcbr. I found the chimney on its inside wholly covered 

 with a greyish layer of C. pipiens, intermixed with a few T. annulata. The tem- 

 perature has undoubtedly been below zero. It was very interesting to observe the 

 behaviour of these mosquitoes. They were wholly immovable; they sat as glued to 

 the walls; if they are taken off, they lie lifeless in the hand on the dorsal side. 

 With regard to thigmotropical phenomena see Weiss (1913 p. 36). If mosquitoes 

 are taken in from the deep dark cellars, brought into the light and kept at tem- 

 peratures about 15° C, they almost always die; probably owing to want of food. Most 

 probably they are not able to keep their metabolism at a point a slow as necessary, if 

 food supply is to be wholly denied. The hibernating mosquitoes are all extremely 

 fat; with regard to this point and to the blood sucking habits I refer to the foll- 

 owing. That it is only the females, which hibernate, that the males die out before 

 winter, and that the hibernating females are impregnated may all be regarded as 

 established facts. 



On a beautifull sunny day in May all the mosquitoes leave the hibernating 

 localities in swarms; on 3/v, a day with bright sunshine, I was told that all the 

 mosquitoes left my cellar as a cloud; the next day I could not find a single one. 

 We do not know where they fly; it is most probable that they fly out to get blood, 

 not being able to ripen their eggs without blood nutriment. Nevertheless we do not hear 

 anything of attacks of C. pipiens in our country, and I myself have suffered no attack 

 from this species in early spring; most probably it satisfies its lust for blood upon 

 poultry, perhaps upon cattle. In June the eggboats are laid in cisterns, water barrels 

 etc. and the larvae appear; the females do not deposit all their eggs in one single 

 batch, but in three or four, and between these batches there passes some time of 



