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Westring, on the stridulation of males of Theridion; on the stridulation of Reduvius personatus; on the stridulation of beetles; on the stridulation of Omaloplia brunnea; on the stridulating organs of the Coleoptera; on sounds produced by Cychrus. Westropp, H.M., on reason in a bear; on the prevalence of certain forms of ornamentation.
Lastly, Westring states that in Omaloplia brunnea the rasp is placed on the pro-sternum, and the scraper on the meta-sternum, the parts thus occupying the under surface of the body, instead of the upper surface as in the Longicorns. We thus see that in the different coleopterous families the stridulating organs are wonderfully diversified in position, but not much in structure.
The males are stridulating by themselves, here and there, teasing the passing fair with their antennae. The future mothers stroll about gravely, with their sabre half-raised. The agitation and feverish excitement means that the great business of pairing is at hand. The fact will escape no practised eye. It is also what I particularly wish to observe.
With some species the males are provided with weapons for fighting; some live in pairs and shew mutual affection; many have the power of stridulating when excited; many are furnished with the most extraordinary horns, apparently for the sake of ornament; and some, which are diurnal in their habits, are gorgeously coloured.
Nevertheless, the power of stridulating is certainly a sexual character in some few Coleoptera. Mr.
With the Coleoptera, however, as before remarked, it is in the great Lamellicorn group, placed by some authors at the head of the Order, and in which we sometimes see a mutual attachment between the sexes, that we find the males of some species possessing weapons for sexual strife, others furnished with wonderful horns, many with stridulating organs, and others ornamented with splendid metallic tints.
Other species of the family to which the Tanana belongs have similar stridulating organs, but in none are these so highly developed as in this insect; they exist always in the males only, the other sex having the edges of the wing-cases quite straight and simple. The mode of producing the sounds and their object have been investigated by several authors with regard to certain European species.
In Geotrupes stercorarius the rasp appeared to me thicker, opaquer, and more prominent in three males than in the same number of females; in order, therefore, to discover whether the sexes differed in their power of stridulating, my son, Mr.
Diversified structures possessed by the males for seizing the females Differences between the sexes, of which the meaning is not understood Difference in size between the sexes Thysanura Diptera Hemiptera Homoptera, musical powers possessed by the males alone Orthoptera, musical instruments of the males, much diversified in structure; pugnacity; colours Neuroptera, sexual differences in colour Hymenoptera, pugnacity and odours Coleoptera, colours; furnished with great horns, apparently as an ornament; battles, stridulating organs generally common to both sexes.
It is also an interesting fact, as bearing on sexual selection, that the stridulating organs of certain male Orthoptera are not fully developed until the last moult; and that the colours of certain male dragon-flies are not fully developed until some little time after their emergence from the pupal state, and when they are ready to breed.
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