T-92. 



HOUSE, GARDEN, AND FIELD 



which sets up a musical sound, such as constitutes the 

 signal to the mate in many flies. Other insects are able 

 to produce sounds by tapping dry leaves, or the wood in 

 or upon which they lurk (see p. 226). No clear case is 

 recorded in which an insect produces a sound by the emis- 

 sion of air from any part of the respiratory system, and 

 the mouth is never concerned. 1 



The chirp of the male cricket is no doubt meant to 

 be heard, both by himself and by some other cricket, 



most probably a female. 

 In a few Orthoptera the 

 female replies to the chirp 

 of the male by a sound 

 which is much less dis- 

 tinctive and prolonged. 

 Signalling backwards and 

 forwards by rasping 

 sounds implies the pos- 

 session of ears or some 

 kind of auditory organs. 

 Where are they to be 

 looked for, and what is 

 likely to be their nature ? 



I suppose that most of us would think the head of the 

 cricket the likeliest place to examine, and the examples 

 of the higher animals suggest that the auditory organ 

 may turn out to be a tense membrane with a special 

 nerve passing to it, such a membrane in fact as the drum 

 of the human ear. There is no membrane on the head 

 of the cricket which can possibly be taken to be auditory, 

 but by searching the body through, membranes which 

 conform to our notion of an ear can be found. They 

 appear in a very strange place, viz. on the fore legs, near 



1 Examples of many cases of sound-production by insects can be found 

 by consulting the index to Dr. Sharp's Insects (Cambridge Natural 

 History) under the headings of Sound-production, Stridulation, and 

 Phonation. 



FIG. 43. Fore tibia of house-cricket, 

 showing the auditory membranes. The 

 outer surface is marked ex, and the inner 

 surface in. 



