[1642] Latreille Organization &c., 199. Chabrier Sur le Vol des Ins. c. i. 412. c. iv. 54, &c.
[1643] In Chlorion, Ammophila, &c., this part separates more readily from the alitrunk.
[1644] Chabrier Sur le Vol des Ins. c. i. 413—. c. iv. 54. This author seems to regard the collar as something peculiar to Hymenoptera.
[1649] M. Chabrier (Vol. des Ins.) supposes that the humming of insects is produced by the exit of the superfluous air from their thoracic spiracles, &c.; in Melolontha he thinks they are in the metathorax under the wings (c. i. 457—. Plate [XXII.] Fig. 13. c. †. represents the operculum of one of those of Dytiscus marginalis): in the Hymenoptera, in the mesothorax, near the posterior lobes of the collar (Ibid. 459. c. iv. 50.); and in the Diptera, in the metathorax, near the poiser (c. i. 457). I observed myself lately, that Elophilus tenax, if held by the anterior part of the body, when it hummed, alternately opened and shut this spiracle. The wings during the sound vibrated intensely. The hum ceased and was renewed, as they were restrained from this motion or released from restraint; when the wing was moved towards the head, a different sound was emitted from that produced when it merely vibrated.