F. M. Howlett 
481 
similar insect 10 mm. long. A very gentle breath of air stimulates fleas 
to great activity. Phlebotomus seems peculiarly sensitive to air-move¬ 
ments, and to this sensitiveness its small size, curious resting-attitude, 
long legs, and long hairy coat probably all contribute (Fig. 1). Mos¬ 
quitoes have similar characters in a somewhat modified form, and they 
are exhibited to some extent by many of the Ghironomidae and by other 
non-bloodsucking Nernocera, but not by Tabanidae, most Muscidae 
(including Glossina) or Hvppoboscidae. 
On more than one occasion when mosquitoes have been troublesome 
at tea-time I have noticed that they seemed to be fond of hovering in the 
neighbourhood of the tea-pot, being attracted apparently by the heat: 
moreover, I have heard it said that during attacks of fever (when the 
temperature of the skin maybe raised above the normal) mosquitoes are 
apt to be more than usually vicious. My own experience rather tends 
to confirm this notion, but of course such an idea may arise merely from 
an increased susceptibility to small annoyances. 
In order to try the effect of heat, several females of 8. scutellaris 
were placed in a loose gauze bag, and a test-tube half full of hot water 
was presented to them in the manner shown in Fig. 2. The effect was 
most interesting. As soon as the hot air from the tube reached the 
insects they became restless and began to congregate on the part of the 
net nearest the tube; as this was brought nearer they became more 
