BY W. R. COLLEDCtE. 



123 



you will be able to distinguish the difference between the head of 

 a ii^entlenian and that of a lady. Here you have a male head 

 in fig. 8 ; the cent'-al organ, the proboscis, is all there, but quite 

 as long as the females ; but look at the palpi how they 

 pise alongside and curve out even further than the 

 proboscis. That alone is a marked difference. In the female 

 they were short not more than one fifth of the length of the 

 organ depicted, although there are exceptions to this rule in 

 some varieties, and then the antennie of this gent has quite a 

 fringe of long hairs which may very fitly be called whiskers. 

 So that there is a decided difference between the sexes. 

 When once you ratch these points, by merely glancing at one on 

 the window or resting anywhere, you can say whether it is male 

 or female. I have in fig. 9 one of these antennte from a gentleman's 

 head, which shows the difierence more strikingly ; it looks like a 

 plume. The hairs are longest at the base, gradually shortening 

 as they approach the tip. The root of these organs is rounded 

 like a ball, and it rests in a cup on the side of the head close to 

 the base of the proboscis. It forms a ball and socket joint and 

 is freely movable. 



It has been discovered that these hairs are musical chords, 

 and the antennae is really the male mosquito's harp. When a 

 tuning-fork giving 512 vibrations per second is sounded, these 

 long hairs are thrown into vigorous motion. The shorter ones 

 respond to other tones. The range of sensitiveness to sounds 

 extends from the middle through to the next higher octave of a 

 pianoforte. That note of 512 vibrations per second is the dom- 

 inant note of the female mosquito when she sings. The harp on 

 the male head is built to respond to the female voice. Whatever 

 other purposes it serves, it is at the same time a delicate musical 

 instrument. 



In the darkness, when the female sings, supposing the male 

 is flying across her position, the sound will be most felt on the 

 branch of the harp nearest to her, for the off-side harp will be 

 partially shielded by his head. Therefore, two series of notes 

 will be conveyed to his brain, stronger on one side, weaker on 

 the other. If he wishes to meet her he has only to wheel round 

 and adjust his position until the sound vibrates on the both 

 harps with equal force. Then, no matter how dense the dark- 

 ness, flying straight forward he will reach her side. Thus her 



