The Buzzing of Diptera. By P. A. Aubin. 333 



modulation, it is not inconceivable that the sound produced may 

 be the means of transmitting a variety of indications to the 

 similarly attuned organs of other individuals. 



The precise part played by buzzing in the life of the individual 

 is somewhat obscure, but the fact that these organs are equally 

 developed and equally efficient in both sexes of Eristalis would 

 seem to indicate some function other than or in addition to a 

 sexual one. 



Such observations as I have been able make on this point are 

 quite insufficient to justify any conclusion, but, so far as they go 

 they indicate that the buzz serves, inter alia, as a warning note to 

 aggressors. 



These observations are as follow : — 



(1; Several of the hover-flies, if held lightly in the fingers, will 

 buzz for comparatively long periods, and many specimens of 

 Eristalis, if held by the legs, will alternate, almost without inter- 

 mission, between buzzing and attempting to fly. 



(2) Most Diptera, when entangled in a spider's web, will buzz 

 at intervals. If quiescent, the captive will almost invariably buzz 

 if the spider, in order to ascertain the nature of its capture, touches 

 it with an investigating claw. 



(3) If a cage containing Eristalis be taken into a partially 

 darkened room, they will cease flying and either remain stationary 

 or crawl about slowly. Under such conditions, should one 

 individual touch another, the one so touched will emit a short 

 sharp buzz which is sometimes responded to by others in the cage. 



(4) A captive, under the Microscope, can usually be made to 

 buzz by touching it with a needle, more especially on the abdomen 

 or wing shoulder. 



The homologues of the parts shown in Plate VIII are easily 

 found in many species of Diptera, inter alia in Caliphora vomitoria, 

 Musca chloris, 31. domestica, Syrphus balteatus, Conops (sp.), and, 

 so far as I have been able to apply the above tests to them, the 

 results are identical. 



Tipula oleracea, in which the various parts can be identified 

 without much difficulty, must be mentioned separately. 



In Plate X drawn from this insect, parts homologous with 

 those in Plate VIII have been given the same numbers for ease of 

 comparison. 



I have been unable to detect any true buzzing in this fly, and 

 from an examination of the parts, I would not expect to do so. 

 Whilst the alulet and. squamae, with their articulation (15, 16, 18) 

 are undeveloped, the articulation 14, compared with fig. 1, is very 

 large. As a result, the wing cannot be closed sufficiently to bring 

 11 in contact with the thorax. The normal position of the wing, 

 at rest, is approximately at right angles to the body, and if it be 

 closed by pressing it inwards, there is resistance until nearly closed, 



