1917] Marchand—N otes on the Habits of the Snow-Fly (Chionea) 149 
glass cage had apparently become too high; however this may be, 
the insect was found dead in the cage in the direct sunlight. The 
other specimen had remained in the shade. In the evening, the 
temperature fell to —11° C., and being curious to know whether the 
Chionea would withstand such low temperatures, I left the glass 
door of the veranda open over night. On the morning of Decem- 
ber 9, the second Chionea was dead, apparently killed by frost, 
after the fashion of the famous tamed herring which had learned 
to walk about and breathe air but one day fell into a pond and was 
drowned. The adaptation to cold has evidently its limits even in 
Chionea, and this insect, although it has its most active stage at 
low temperatures, seems to withstand freezing less than many 
other insects which at low temperatures become entirely passive. 
The possibility that the males have normally a shorter life than 
the females should, however, be taken into consideration, and may 
partly account for their rapid death. The factor of humidity may 
also be of importance, and ‘death in the bright sunlight may be due 
to increased evaporation as well as to the temperature. 
CONCLUSIONS. 
Chionea is not an accidental guest on the snow but perfectly 
adapted to life on the snow by its habits. This is evident from the 
fact that it can move about on snow for a practically indefinite 
time without being frozen, while most other insects which may be 
collected on the snow have been carried there by air currents or 
attracted by the strong light, but do not run about on the snow 
and usually perish within a few hours on the spot where they have 
fallen. Furthermore, the Chionea regularly drinks water from 
the snow by pressing its proboscis against it as was repeatedly 
observed. 
Chionea is attracted to the snow: 
(1) By the bright light and white color of the snow (+-phototro- 
pism) ; 
(2) By a thermotropic reaction which is, in itself, stronger than 
the phototropic reaction and which increases in the light (— thermo- 
tropism) ; 
(3) By the peculiar contact of the snow and a direct stimulus 
resulting from the action of cold on the claws (special temperature- 
sensibility ?). 
