90 INSECT MISCELLANIES. 



which were at a good distance from the spot where we 

 stood, — the primary cause, perhaps, of their flying 

 high.* 



' That purely rural, Httle noticed, and, indeed, local 

 occurrence,' says Mr Knapp, ' called by the country 

 people ^' hummings in the air," is annually heard in 

 one or two fields near my dwelling. About the middle 

 of the day, perhaps from twelve o'clock till two, on a 

 few calm, sultry days in July, we occasionally hear, 

 when in particular places, the humming of apparently 

 a large swarm of bees. It is generally in some spa- 

 cious open spot that this murmuring first arrests our 

 attention. As we move onward the sound becomes 

 fainter, and by degrees is no longer audible. That 

 this sound proceeds from a collection of bees, or some 

 such insects, high in the air, there can be no doubt ; 

 yet the musicians are invisible. At these times, a 

 solitary insect or so may be observed here and there, 

 occupied in its usual employ, but this straggler takes 

 no part in our aerial orchestra. '| 



The buz of flies has been found no less diflicult to 

 explain than the hum of bees. That it is not pro- 

 duced by the wings alone striking upon the air, is 

 proved from the fact of many insects of rapid flight, 

 such as the dragon flies {LibeUidina) and the crane 

 flies (Tipulidce), Rying silently. Some flies, again, 

 are able to produce a loud buz when not on the 

 wing. Of this, an instance has recently occurred 

 to us in the wasp fly ( Chrysotoxiim fasciolatum^ 

 Meigen), which had got into our study, and kept up 

 its peculiar buz when resting, apparently motionless, 

 on the window-frame ; yet, when we observed it mi- 

 nutely, there was still a perceptible vibratory tremor 

 in the wings, similar to that of a harp-string, but so 

 rapid as at first to escape the eye. The same buz 



* J. R. 



+ Journ. of a Naturalist, p. 376, 3d edit. 



