68 MORE MINOR HORRORS 



The song of the female vibrates the fibrillae 

 of one of the antennae more forcibly than those 

 of the other. The insect spreads the angle between 

 his antennae, and thus, as I have observed, brings 

 the fibrillae, situated within the angle formed by 

 the antennae, in a direction approximately parallel 

 to the axis of the body. The mosquito now turns 

 his body in the direction of that antenna whose 

 fibrils are most affected, and thus gives greater 

 intensity to the vibrations of the fibrils of the other 

 antenna. When he has thus brought the vibrations 

 of the antennae to equality of intensity he has placed 

 his body in the direction of the radiation of the sound, 

 and he directs his flight accordingly, and from my 

 experiments it would appear that he can thus guide 

 himself to within 5° of the direction of the female. 



There has always been some divergence 

 of opinion as to how the buzzing sound to 

 which the male so readily reacts is produced. 

 Howard once thought that it was due to vibra- 

 tions of certain chitinous processes in the large 

 tracheae. Our experiments showed, however, 

 that when the wing was cut off closer and 

 closer to its origin the sound decreased in 

 volume, but the note progressively rose. Un- 

 like human beings, the male at all times emits 

 a higher pitched note than the female, and in 

 both sexes the note rises after feeding. ' The 

 greater the meal, the higher the note.' This 

 is, however, by no means confined to mosquitos. 

 It is a matter which any one must have noticed 



