70 BIOLOGY OF ADULT MOSQUITO [CH. 



Sound. We have already referred to the stridulating 

 apparatus described by Shipley and Wilson, by means of 

 which the insect emits a sound whilst flying. Certain males 

 seem to be very susceptible to notes resembling the hum of 

 the female and the insects have been noticed to swarm around 

 instruments emitting particular notes. At Grantchester, near 

 Cambridge, where Anopheles maculipennis and Culex pipiens 

 are fairly common, the writer has noticed that these insects 

 may be aroused to activity by the sound of a piano or violin. 



Howard was informed by Mr A. De P. Weaver, that while 

 engaged in some experiments in harmonic telegraphy, in 

 which a musical note of a certain pitch was produced by 

 electrical means, he found that when the note was raised to 

 a certain number of vibrations per second, all mosquitoes, not 

 only in the same room but also from other parts, would con- 

 gregate near the apparatus and would be precipitated from 

 the air with considerable force. He therefore covered a large 

 surface with sticky fly-paper and after sounding the note for 

 a few seconds caught all the mosquitoes in the vicinity. 



Habitat and modes of dissemination. As a rule mosquitoes 

 do not wander more than one or two hundred yards from their 

 breeding places (see page 72). Nevertheless, occasionally 

 migratory flights have been noticed during which the insects 

 travelled many miles. Such a mode of dissemination, how- 

 ever, is certainly very rare and generally mosquitoes are spread 

 by human agency. Ships and trains are both responsible for 

 the introduction of species into fresh localities, as the females 

 may remain in the holds of ships or in the carriages of trains 

 for several days, and thus be carried hundreds of miles. The 

 occurrence of certain species at scattered seaports in various 

 parts of the world shews that this mode of dissemination has 

 been of considerable importance in the past, when ships carried 

 unprotected tanks of water. 



Resting position. When at rest an Anopheline can generally 

 be distinguished from a Culicine by the attitude of the body 

 and the legs. Anophelines usually rest with the proboscis 

 pointing towards the surface, and as the proboscis and the rest 

 of the body are in a straight line, the insect has a very 



