F. M. Howlett 
187 
was stopped they had laid a few eggs (about a dozen) on clothing, but 
none were discovered on hairs. After these eggs and all the lice had 
been removed, none subsequently hatched on the body, as they would 
have done had any eggs been laid on hairs and escaped detection. 
II. A TEMPERATURE-REACTION OF LlCE AND MOSQUITOES. 
Some years ago I described the curious action of warm surfaces in 
stimulating female mosquitoes to bite. A glass tube full of hot water 
was brought near the net cage in which mosquitoes were confined, and 
they made attempts (more or less vigorous according to the species 
of mosquito) to bite the warm surface of the tube, their efforts in the 
case of several species being extremely vigorous. 
1 should correct here an error made in that paper: it was stated that 
one of the species which exhibited the reaction was Culex fatigans. 
In reality the Culex referred to was an unidentified species, and should 
read Culex sp. The paper was written in England, and on returning 
to India I not only discovered the error, but found that it was a rather 
unfortunate one, as on carrying out some further experiments with 
accurately identified fatigans it became evident that they did not react 
to the hot tube, but formed a marked and curious exception to the 
rest of the species experimented with, of which the majority gave a 
very definitely positive reaction. 
It is noteworthy that this temperature-reaction in mosquitoes is 
exhibited only by females, and it should probably be regarded as a 
normal component of the blood-sucking habit. The case of Phlebotomus, 
which sucks blood from cold-blooded animals as well as from man, has 
not yet been investigated but might give results of interest. In 1911 
I made some observations on the rat-flea without getting any very 
definite results, but the experiments were ill-devised and not conclusive: 
as far as they went they seemed to indicate the absence of any definite 
positive reaction such as is found in mosquitoes. When circumstances 
permit I hope to take up this investigation again with the object of 
ascertaining in what way and to what extent the reaction to warm 
surfaces is exhibited by each of the different groups of insects which 
suck blood from warm-blooded animals. 
In the case of Pediculus humanus, the head- and body-louse, I have 
made some rough observations on the effect of bringing warm objects 
near the insect. A quarter-inch tube of thin glass filled with hot water 
was generally used, its temperature being between 35° and 50° C. The 
effect of bringing such a tube within an inch or so of a louse is to stimulate 
