MANDUCA ATROPOS. 451 



frons and vertex. The space here between the frons and this 

 special sac cavity is occupied by a rete mirabile of tracheal 

 tubes and over this area the roof of the sac is soft and flaccid, 

 and capable of considerable movement, so much as to amount 

 probably to complete collapse of the cavity when it is depressed. 

 This cavity appeared to be a dilated upper end of the oesophagus, 

 its structure appearing to be continuous with the oesophagus, 

 but I did not succeed in passing a bristle from the cavity into 

 the oesophagus. The primary function of this cavity seemed 

 probably to be to produce a sucking vacuum at the base of the 

 proboscis to draw up honey or other fluids *, its method of action 

 being the alternate turgescence and exhaustion of the tracheal 

 spaces above and also around it, produced probably by the 

 abdominal movements, and utilised by the valvular action ot its 

 openings. It seemed to me that air, either drawn into or expelled 

 from this sac through the valvular opening at the base of the 

 proboscis, was the cause of the cry. I entirely failed, however, 

 to obtain a view of this opening or chink during vocalisation 

 and so am unable to feel absolutely sure that this is really 

 a vocal organ. That my conclusion, however, is the same as 

 Mr. Moseley's and was reached without the prompting of previous 

 information gives his view strong support." Poulton is said 

 (Ent. Rec, xii., p. 350) to have asserted that, with a stethoscope 

 (for both ears) ending in a fine tube, he was able to locate the 

 sound, and that, when the tube is placed against the part whence the 

 cry comes, one is deafened by sound, whilst everywhere else over 

 the body it is very faint. His detailed conclusions agree with those of 

 Moseley. Ullyett notes ( Ent. Mo. Mag., v., p. 171) that a specimen of M. 

 apropos, found in Folkestone Warren in September, 1868, was kept for a 

 few days and until it died a natural death. It frequently emitted the 

 sound peculiar to its species, always raising the thorax and bending 

 down the head and abdomen as it did so. When breathing its last, 

 it gave out a long succession of sounds, growing fainter and fainter, 

 just like a succession of breathings, giving one the impression that 

 the noise was produced not by friction, but by inspiration and respiration 

 of air. Ullyett says that it made the noise when he first had the moth 

 every time he merely touched it with his finger, but when it got accus- 

 tomed to such treatment it never made it without rather rougher 

 handling. Swinton also asserts {Ent. Mo. Mag., xiii., p. 219) that, when 

 the insect squeaks, the two large air-vesicles at the anterior part of the 

 abdomen are generally inflated by an unusual spasmodic compression 

 of the posterior segments beneath, and that the yellow fan or fascicle of 

 hairs, rising perpendicularly from a fold at either side, emits a pungent 

 scent of jessamine and expands to a stellate form. This action led 

 to the theories of Lorey and Nordmann, already noted, whilst its 

 appearance seems also to have led Wagner to conceive that air was 

 then forced into the cleft haustellum. This particular has a new value 

 now that we have Head's note (anted, pp. 435-436) as to the mode of 

 copulation, and there would appear to be no doubt that the cry is utilised 

 by the sexes to attract each other, that, in nature, it is used when the 



*Taschenberg is reported to have stated that he found a specimen of M. 

 atropos in a beehive, which squeaked quite loudly and distinctly, although its 

 " sucking-bladder " was full of honey instead of air. 



