88 



without trees around. The eggs are hatched, in autumn when the ponds get water 

 again. Before winter they are full grown, and as such they winter, living under the 

 ice exactly like C. morsitans. In the first days of May they pupate, and the mos- 

 quitoes appear in the first part of the same month. In the aquaria they almost 

 always lie upon the bottom and only rarely come to the surface; w 7 ith their short 

 flabellae they brush the bottom and gather their food in this way. If there are water 

 plants in the aquarium, I have seen them follow 7 the leaves and stems, go round 

 the leaves, holding the axis of the body in a very acute angle to the leaf, simul- 

 taneously pressing the flabellae against the leaf and slowly move forward cleaning it 

 from adherent particles. It looks rather peculiar to see the larva without any cling- 

 ing or grasping organs slowly slide over the under side of the leaves, using the 

 flabellae simultaneously as an organ for nutriment and for movement. But in another 

 respect, too, the larvae are peculiar. More than the other, hitherto observed mos- 

 quito larvae they stand still in the water layers; \vithout reaching either the surface 

 or the bottom, the larvae, always standing perpendicular, first ascend a little and 

 then slowly sink downwards then swim a little actively and horizontally and then 

 again stand perpendicular for slow ascent or descent. I have tried to see, if an air- 

 bubble would appear on the apex of the sipho during these movements and prob- 

 ably alter its size, but I have never seen anything of that kind. When I had diffe- 

 rent species of mosquito larvae in the vessels, I was always able to distinguish the 

 larva of 0. rusticus from other mosquito larvae owing to this power of suspension 

 in the water layers below 7 the surface. 



Though I have rather often found the larva in the neighbourhood in Hillerod 

 I have hardly ever seen the imago in Nature. In 1920 ( 26 /v) when I was on an 

 excursion upon Amager to my astonishment I was attacked by enormous masses 

 of 0. rusticus. Often more than twenty were sitting upon my clothes, trying to get 

 blood; they stung vigorously. The attack began at about seven o'clock and was 

 unaltered, when I left the place at half part eight. The specimens were larger than 

 those I have hatched from the forest ponds; their hatching ponds I did not succeed 

 in finding. Collections from the first days in June did not show a single 0. ru- 

 sticus; at that time immense numbers of O. latescens appeared, which had just be- 

 gun to sting by 26/v. 



Geographical distribution: The species has hitherto only been recorded 

 from Italy, Macedonia and England. 



14. O. diantaeus (Howard, Dyar and Knab). 



Tab. XIII. 



Description. Female: Proboscis moderately long, curved, labellae conically 

 tapered, vestiture black, but with many intermixed greyish scales; labellae black. 

 Palpi short; only about one-sixth as long as proboscis; vestiture black, some white 

 scales at apex. Antennae filiform; the joints subequal, rugose, pilose; second joint 

 enlarged, bright; the others black, with grey scales and outstanding greyish hairs; 



