498 Records of the Indian Museum. [Vor,. X1, 
fig. 5; quoted in Fauna of British India, Lamellicornia, I, p. 
265). ! 
Concerning the action of the stridulating organs of Oryctes 
rhinoceros nothing yet seems to have been published. I have had 
great difficulty in obtaining any evidence as to the use of the so- 
called stridulating organ found in the larva (pl. xxii, fig. 1). When 
a specimen is tightly held by the head, however, it may be seen to 
move the mandibles and maxillae in a manner likely to bring the 
organ into action, and a faint rasping sound may sometimes be 
heard if the specimen be brought close to the ear. No definite 
vibrations have been felt, and the movements of the mandibles and 
maxillae are those which would probably be used, in order to free 
itself, by any insect similarly placed. Pressure on the body does 
not seem to induce any such movements, but they are sometimes 
indulged in by larvae which find themselves on their backs on a hard 
surface in the open. The movements are often greater in extent 
than their use for stridulatory purposes requires; the mandibular 
part of the organ is, indeed, sometimes fully exposed at intervals, 
and could not then be scraped at all by the maxillary portion. 
The rasping seems, nevertheless, to be produced only when these 
movements occur. It is therefore probable that it is produced by 
the organs in question, and it is noteworthy that the movement 
of the mandibles and maxillae is often very small—as it should be 
to keep the two parts of the organ in contact—and that this does 
not interfere with the sound produced. 
The pupa, in which no stridulating organs appear to have 
been described, stridulates quite audibly when disturbed. The 
sounds are produced as the result of backward and forward move- 
ments of the abdomen, movements which cause a pair of scrapers 
situated on the dorsal part of the anterior margins of segments 
2-6 to rub over the faintly ridged surface of the hard chitinous 
walls of oval depressions on the posterior parts of segments I-5 
(pl. xxii, figs. 2-3), producing vibrations through the whole pupa, 
as well as sound. The organs are very conspicuous in living speci- 
mens, but in preserved ones they are apt to be largely hidden 
between the terga. The organ between segments 6 and 7 is rudi- 
mentary.” 
I have heard the adult stridulate, but not loudly. The sound 
appears to be produced by the rubbing of the well-known ridges on 
the posterior end of the abdomen against the posterior ends of the 
elytra (pl. xxii, fig. 4), but I have not yet been able to investi- 
gate this as fully as I would like. 
where it is most unlikely to attract the attention of those interested (¥.A.S.B., 
XII, Pp: 421-437), of a coloured figure of Lupatorus hardwickei from the summit 
of the Gogur Range, gooo ft., in Kumaon. 
' See also Rutherford, Spolia Zeylanica, X, p. 77. 
* Similar structures are present in the pupae of several other beetles—e.g. 
Adoretus (Rutelinae) and Hectarthrum (Cucujidae)—but they do not appear to be 
stridulatory on any segments in them. 
