BRACHELYTRA. 



613 



Wage is occasioned by the attraction afforded by the 

 scent of some new-laid dung upon or near the spot, 

 and upon which they feed with avidity. It is pre- 

 cisely in the same manner that the species of the 

 brachelytra swarm in the same situations. How often 

 is it that, in walking along some shady lane in the 

 heat of the summer, we have been half blinded by 

 these little torments flying unconsciously into our 

 eyes, occasioning a smarting pain, greatly increased 

 by the emission of the fluid or vapour which, as above 

 stated, these insects have the means of discharging, 

 and which has terminated only by the extraction of 

 the little animal, which, instead of a choice repast*, 

 has found, in all probability, a watery grave. This 

 continued searching after their food has caused these 

 insects to be termed rove-beetles in our common 

 language ; and the circumstance, that a group of 

 insects should have received a general vernacular 

 term in England, (that of rove beetles,) whilst the 

 numerous continental entomologists have not con- 

 ferred upon it any other than its scientific denomi- 

 nation, is one which, although it may appear to be 

 unworthy of notice, is a striking indication of that 

 peculiarity in the geographical distribution of these 

 insects to which we have above alluded. 



In Great Britain, we possess nearly eight hundred 

 species, described by Mr. Stephens. Now, De Jean, 

 in the new edition of his Catalogue of Coleoptera from 

 all Quarters of the Globe (1833), does not enumerate 

 more than this number. From the tropical climes of 

 Asia and America we possess scarcely any species. 

 In fact, Great Britain has been regarded as the me- 

 tropolis of the group ; and it is a singular circum- 

 stance, that not a single insect of the brachelytra 

 was collected by Dr. Horsfield during his long re- 

 searches in Java. That they sparingly exist in that 

 country cannot perhaps be doubted, because, both 

 from India and New Holland have species been 

 received, but in all those parts of the world their 

 numbers are very trifling indeed. Let us look, how- 

 ever, at the cause of this, and its apparent singularity 

 vanishes. " In Java, as in all other tropical climates, 

 the surface of the earth is almost exclusively occupied 

 by ants ; and, according to Dr. Horsfield, when the 

 common ants are not found, the termites, or white 

 ants, possess the territory. These two tribes, which 

 are constantly at war, or rather, which clear away 

 and destroy each other as their numbers respectively 

 predominate, have in a great measure divided the 

 surface of the island among themselves. From their 

 incredible numbers, particularly of the common ant, 

 little is left on the surface for other insects. Swarming 

 in every spot, and incessantly in motion, they attack 

 and devour whatever animal matter they meet with 

 in a much shorter period than would be thought 

 possible by a person who had not witnessed the fact. 

 But, nevertheless, whenever, in his excursions, Dr. 

 Horsfield observed the carcass of any animal, he and 

 his assistants carefully examined it, and, from the care 

 they took in such labours, he is convinced that, had sil- 

 phidae, staphylirrida?, and such mv'o-feeding families 

 of insects occurred in an}' tolerable abundance, they 

 would scarcely have escaped his researches. With 

 respect to such genera of brachelytra as inhabit 

 flowers, he scarcely conceives, had they been common, 



that they would have escaped him, as he was in the 

 constant habit of collecting on plants and flowers." 

 MacLeay, Annulosa Javanica. This author, it will be 

 seen, speaks only of carrion feeders, and those inhabit- 

 ing flowers ; but the fact of their feeding upon decay- 

 ing vegetable matter is known to every practical 

 entomologist. Indeed, from this circumstance one of 

 the genera has derived its name. See the article 



BOLETOBIUS. 



Some species, forming the genera PcEdcrus and 

 Stenus, are generally found upon the margins of streams 



Practical collectors of insects are well aware that the most 

 advantageous method of obtaining these insects is to immerse 

 pieces of dung:, or such like matters, in a pail of water, when 

 tlie beetles rise to the surface, and are easily secured. 



ttor standing water, whilst others, of a small size, 

 s the Omalia, frequent flowers in the perfect state. 



The larvte nearly resemble the perfect insects in 

 shape, being long and narrow, with the head broad 

 and large, but the wings and wing-covers are entirely 

 wanting ; the legs, which are six in number, are 

 attached to the first three segments of the body, 

 which gradually becomes more slender to the extre- 

 mity, terminating in an elongated tube, armed at 

 each side with a long and slender hairy jointed 

 filament. These larvae are found in the same situations, 

 and prey upon the same substances as the perfect 

 insects. 



In the Linnaean system only twenty-six species 

 belonging to this sub-section were described under 

 the genus Slaphylinns. As, however, the group 

 became better known, and the number of species 

 greatly augmented, various generic groups were 

 detached by Fabricius, Gravenhorst, and others. 

 The group was, however, restored to its original 

 limits, by its establishment as a distinct sub-section, 

 comprising numerous genera, and by the distribution 

 of the latter, according to the comprehensive views 

 of Latreille, into several tribes ; namely, 1. the 

 Fissilabres (cleft-lipped) ; 2. Longipalpi (having long 

 palpi) ; 3. the Denticrura (having toothed tibia?) ; 4. 

 the Depressa (flattened bodies) ; and 5. the Micro- 

 cephala (small-headed). To these tribes the Count 

 Mannerheim, in a valuable memoir upon this family, 

 contained in the first volume of the Memoirs of the 

 Imperial Academy of Sciences of St. Petersburg, 

 has added another, under the name of the Aleocharides, 

 a step which we had long previously proposed in a 

 memoir upon these insects, published in the Zoolo- 

 gical Journal. To these another group is also re- 

 ferable, namely, the extraordinary family of Psela- 

 phidce, which, from having been supposed to possess 

 only two joints in the tarsi, had been formed by 

 Latreille into a distinct primary section of the Cole- 

 optcra, under the name of Dimcra. As, however, 

 their general structure agrees with some of the minute 

 brachelytra, and as some of the latter have only three 

 joints in the tarsi, the grounds for their separation 

 become untenable, and they have accordingly, by 

 Messrs. MacLeay and Stephens, been introduced into 

 the brachelytra. 



As the work of Count Mannerheim is the latest 

 containing a general revision of the group, and more- 

 over, as it is in the hands of very few English ento- 

 mologists, we have thought that the following slight 

 synopsis of the classification contained in it may not 

 be uninteresting to our readers, premising only, that 

 some other genera have been described by Mr. 

 Stephens in his Illustrations of British Entomology, 

 and of which the Count Mannerheim was ignorant. 

 Tribe 1. STAPHYLINIDES (Finsilabra, Latreille). 

 The head is separated from the thorax by a narrow 

 neck, so as to be entirely disengaged ; the thorax is 

 square, semi-oval, rounded or truncate-cordate ; the 



