1913.] 37 



On the humming of Chironomidx. — In the " Entomologist's Monthly 

 Magazine" of November, 1912, is an interesting commvxnication by Mr. Clavide 

 Morley on " The Cause of Humming in the Air." After attributing the sound 

 to certain Chironomidae, Mr. Morley draws attention to the fact that his present 

 observation is only the second reference to the prodviction of sound by insects 

 of this family. Perhaps the following instance may be of interest as a third 

 record : — 



Colombo is plagued at certain seasons by dense swarms of so-called " lake- 

 flies," which issue at night-fall from the margins of the shallow lake that 

 spreads its many arms through the residential quarters of the town. These 

 flies are Chironomids of a species that has been described recently by Kieffer, 

 under the name of Chironomus ccylanicus. Bungalows situated on the leeward 

 side of the water are rendered almost uninhabitable during the fly season, when 

 the insects swarm into the lighted rooms, blackening the walls upon whicli they 

 settle and making themselves generally objectionable. In the morning they 

 may be swept up literally by the bushel. 



I happened to be bicycling one evening along a I'oad that impinged — at one 

 point — upon an arm of the lake. On approaching this spot I became aware of 

 a gradually increasing and insistent noise that I stipposed to be emanating from 

 some powerful machinery in rapid motion, and I was wondering what factory 

 could be in activity at that time and place, when I sixddenly was involved in a 

 dense fog of flying insects. I was instantly smothered in flies which filled my 

 eyes, ears and nose, almost blinding and suffocating me. I had to dismount 

 hiirriedly and grope my way through the living cx"Owd until the road fortunately 

 took a sharp tiu-n away from the water and I found myself in a clearer 

 atmosphere. 



On this particular evening the air was comparatively still, and what little 

 breeze there may have been was blocked by a high wall on the opposite side of 

 the road. Consequently, the flies that were rising in clouds from the herbage 

 where they had been resting during the day, together with the swarms that had 

 freshly emerged from the water, were unable to disperse themselves as rapidly 

 as in the more open parts, and had become densely packed in the confined space. 

 The noise which, at the time, I supposed to be produced by the vibration of the 

 myriad wings, was most extraordinary. I now understand that it is more 

 probably attributable to actual stridvilation. This is confirmed by the fact that 

 a single Chironomus if, as often happens, it blunders into one's ear, makes itself 

 audibly perceptible by a shrill note reseml)ling that of certain mosquitoes. — 

 E. Ernest G-reen, Peradeniya, Ceylon : November 25th, 1912. 



[I find the following note in my diary for January 25th, 1904, when calling 

 at Colombo on the homeward voyage from Austi-alia : — " In passing the shore 

 of the extensive fresh-water lagoon at the back of Colombo shortly after sunset, 

 I was greatly struck with the enormous nvimber of small harmless gnats on the 

 wing. They could be seen quite a long way off, in dense swarms looking like 

 colvimns of smoke or dust on the road, and on entering one of these swarms the 

 air was filled with the sharp hiun of myriads of wings." — J.J.W.] 



