. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 366 Mr. P. W. Edwards on specimens, however, I was astonished to find, first that the insects were only about half as large as they appeared to be when on the wing, and secondly that the swarm consisted exclusively of females of Palpomyia brachialis, Hal. The fact that only females were present seemed sufficiently remark- able, for, as is well known, these dancing swarms of Chiro- nomidse and other Diptera nearly always consist of miles only, and are often an essential prelimi
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 366 Mr. P. W. Edwards on specimens, however, I was astonished to find, first that the insects were only about half as large as they appeared to be when on the wing, and secondly that the swarm consisted exclusively of females of Palpomyia brachialis, Hal. The fact that only females were present seemed sufficiently remark- able, for, as is well known, these dancing swarms of Chiro- nomidse and other Diptera nearly always consist of miles only, and are often an essential preliminary to copulation, the females flying into the swarm one by one, pairing, and the pairs dropping out. There was, however, something still more remarkable about these insects. By accident I squeezed one of the flies between my fingers, and noticed that some curious reddish tubes were being everted from the end of the abdomen. Subsequent examina- tion of other specimens confirmed the presence of these tubes, and by careful observation of the insects on the wing it was ascertained that the tubes were always fully everted during flight, the position in which they wrere held being made out with some accuracy. When the specimens were taken in the net the tubes were withdrawn into the body with amazing rapidity, so that by the time the flies could be examined there was rarely a trace of the tubes visible exter- nally. This, then, was the explanation of the apparent discrepancy in size between the flying and the captured Palpomyia brachialis, Hal. Flying attitude. The accompanying diagram shows the arrangement of the fully extended tubes while the insect is in flight. The tubes arise from openings in the membrane at the bases of some of the abdominal segments. There is a pair at the bases of each of segments 5-7, each tube being nearly as long as three. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability
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