75 



left the pond, has not passed the second ecdysis; it will unquestionably he devoured 

 hy more vigorous comrades. 



As always in the Culicidse, the males appear a few days before the females; 

 during the first days the vegetation round the ponds is covered with males; then 

 they disappear and we next find them in large dancing swarms in the glades and 

 on the wind-protected edges of the wood. Especially if the weather is cold, we do 

 not suffer from 0. communis till a fortnight after ecclosion (see later); then sud- 

 denly comes the week, when the lust of blood awakes in the millions of mosqui- 

 toes hatched in May from the numerous woodland ponds. In the vast forests of 

 North-Seeland I have observed how the swarms in May are restricted to the very 

 ponds in which they are hatched; but later on, especially in the middle of June, 

 the swarms are fused together and, everywhere in the forest, horses as well as men 

 are attacked. As an exclusive forest mosquito it hardly ever goes out of the forest ; 

 according to my experience, the attack is always worst in the biggest and darkest 

 part; here in the deep shade the attack on a sunny day at noon is just as severe 

 as in the evening. In late spring and early summer man and cattle are almost ex- 

 clusively injured by this single species. 



The mighty attack of 0. communis lasts only two or three weeks; before the 

 end of July other species displace it, but even in September, though rarely, we are 

 subject to its sting. 



When, in July, the female is going to deposit her eggs, she commonly finds 

 only quite dried up ponds everywhere; where, in spring, bright little mirrors of 

 water broke the monotonous green carpet only greyish-brown spots surrounded by 

 or quite overgrown with Cyperacese etc. are found on the forestground. 



For three years I vainly tried to see the process of egglaying. Not until the 

 summer of 1919 on 3/vn did I have an opportunity to observe it in one of the 

 wholly dried up Mochlony x-ponds. The females were sitting under the dry leaves; 

 here, as many times before, I had placed myself on one of the Carex-tufts eagerly 

 observing every grass-stem and every leaf, hoping that here I should see something 

 of the process. Once after having turned over the withered leaves, I found, in a 

 layer of leaves below those rolled up by the sun, some mosquitoes which slowly 

 flew away. Looking at these leaves with a lens I found them sprinkled with the 

 well-known black mosquito eggs. Later on, leaves which were cleaned were brought 

 into the laboratory and placed in a vessel together with several females; the next 

 day I found the same black eggs scattered over the bottom under the leaves. 

 Therefore we can now take it for granted that this species probably, like all our 

 other OcMerotatus-species, lay their eggs on dry earth and singly. I interpret the 

 life-cyclus of 0. communis as follows: 



The eggs are hatched in midwinter or in very early spring; many of them 

 do not hatch before April; owing to the rising tp. the latest hatched overtake the 

 first, and in the two first weeks of May the mosquitoes are hatched. The mating 

 process takes place shortly after hatching, but the craving for blood does not appear 



10* 



