Insects. 



6149 



a liftht on the matter. I found an ants* nest which for some cause or other had been 

 deserted since last year at least; it was a large heap, as much as a cart-load, quite 

 intact, like the other ants' nests full of Onisci, luli, Scolopendrae and Acari, but 

 without a sinjL!;le aiit living in it. I took a portion from the top, spread it out on a 

 sheet of white paper in the same manner as I had done from the nests that were full 

 of ants, and soon had the pleasure of seeing some beetles moving among the debris. 

 I repeated the process, and eventually found I had the following species, the relative 

 numbers of each being about the same as in the other nests, except that Sapriniis 

 piceus was much more numerous: — Dendrophilus pygmseus, Saprinus piceus, 

 Monotoma angusticollis, M. conicicollis, Trichopteryx sericans, T. atomaria, Cephen- 

 nium thoracicus,Leptacinus Formicetorum,Thiasophila angulata, Oxypoda haemorrhoa, 

 O. formicetorum, Quedius brevis. There were also many beetle larvae moving about. 

 It was therefore not only clear that that the Onisci were in no way dependent upon 

 the ants, but that those beetles I have mentioned, which are usually found in nests of 

 Formica rufa, have no necessary connection with the ants, but merely take advantage 

 of the circumstances favourable to their existence, which are incidental to the nests, 

 such as the decaying wood and vegetable matter, the heat which is considerably 

 greater than that of the atmosphere, and the Acari and other small creatures which 

 abound. The xylophagous beetles, I have no doubt, feed on the wood, the car- 

 nivorous on the Acari, &c., which are fostered by the heat. It is certainly curious 

 that ceitain species of ants have for lodgers only certain species of beetles; 

 it has been surmised that the formic acid of the ants has an attraction for most of the 

 beetles, and it may be so, but I am inclined to the opinion that investigation will 

 show that in many cases where a direct connection with the ants is now supposed to 

 exist, it is merely some contingent circumstance that causes the beetles to frequent 

 the ants' nests. While we cannot disbelieve the statement of Miiller and others that 

 Claviger foveolatus secretes a fluid which is eagerly taken by Formica flava, in whose 

 nests this beetle is found, and that the ants in return feed the beetles from their own 

 mouths and carry them out of the way of danger, yet it is possible that there has been 

 some error of observation, for similar statements have been made with regard to the 

 Paussidae found in ants' nests, and yet the facts have been deemed susceptible of very 

 different interpretations. Herr Gueinzius, writing about the Paussidae of Port Natal, 

 says (Proceed. Ent. Soc. 1851, p. 106), I saw a long train of ants busily running 

 backwards and forwards, and I remarked among them a Pentaplatarthrus gently led 

 by its antennae by several ants, which accompanied it in the common procession. My 

 first idea, that it was forcibly held against its will, 1 gave up, when on this and 

 following days I several times saw the same fact occur on the approach of a thunder- 

 storm.'' But Mr. Plant, also writing from Port Natal, says of tlie Paussidae (Proceed. 

 Ent. Soc. 1855, p. 121), "Respecting their habits, I think the notion that they live 

 with the ants, or are at all desirous of their society, is an error: all that I saw were 

 close prisoners and jealously guarded. The beetles are in the bottom of the tufts of 

 grass, and owing to the small size and matted nature of the herbage, are very dif- 

 ficult to discover in that position, but it is the business of the ants to find them, and 

 well they perform it. The ants do not kill them on the spot simply because they can 

 convey them home alive. * * * The sum of my observations amounts to this: — 

 the Paussi do not seek the ants nor remain with them voluntarily; on the contrary, 

 they use every possible exertion to escape, though not one that I saw succeeded in 

 doing so, they are captives to the ants ; and for what other purpose should the latter 



