196 



Marvels of the Universe 



fatal vengeance as does the Russian Feather- 

 grass. This is only one of innumerable instances 

 of the indifference shown by Nature to the 

 suffering of individuals in her solicitude for the 

 perpetuation of various species. 



Plmlo lif] 



The Dor-beetl( 



[J. J. \V„r,l. F.E.X 

 THE DOR-BEETLE. 



is the thicli-set blue-blacU insect that fre- 

 quently blunders against us as it flies. Owing to the mites 

 that swarm upon its lower surface, it is often called the Lousy 

 Watchman, 



THE DOR-BEETLES MITE 



BY JOHN J. WARD. F.E.S. 



The Dor-beetle, in its polished armour of what 

 looks like burnished steel, is a familiar creature 

 during the autumn evenings. Since, however, 

 the similar story of its near relation, the Sacred 

 Scarab, has already been told in this work. I 

 need write but little here concerning it. My 

 present consideration is of the host of tiny 

 guests that usually accompany the beetle. 



When, in its hurried flight, the beetle has 

 collided with some object, it is not infrequently 

 found on its back on a hard road or path, 

 kicking its very hardest with its si.x legs, and 

 yet quite unable to get its feet upon the ground. 

 The metallic blues and purples of its underside 

 show to perfection as it struggles, and it is at 

 such a moment that we are tempted to pick up 

 the insect. How often, though, have we im- 

 mediatelv dropped it again — on account of the 

 are almost invariably found clinging to its 



crowd of little, pale yellow " parasites " that 

 body and legs ? 



One da}.' I removed from a small-sized beetle forty-three of these mites — one of which is shown 

 in the accompanying photo-micrograph — but that is a comparatively small number, for sometimes 

 the}' literalh' swarm over the beetle. Yet, strange to relate, it never seems the least bit incon- 

 venienced on their account ; there is, I think, a plausible explanation of that curious fact. 



In the first place I would like to call attention to the clean state in which the beetle is always 

 found. Considering the noisome substances which it manipulates, and into which it completely 

 burrows, it is rather surprising that it should not carry with it some trace of its labours ; but it does 

 not even retain the odour of its surroundings. The latter is the more remarkable when we take into 

 consideration the fact that the ill-savoured burying beetles make their presence known in no 

 unmistakable mamier ; but with burjdng beetles the Dor-beetle's mite apparentlj^ has no 

 connection. 



Since the beetle's body and legs are clothed in a horny armour, we naturally wonder on what 

 the mites subsist ; for it seems impossible for such tin}' creatures to penetrate so hard a surface 

 as that of their host. Also, they never appear to be sucking the beetle's blood. More often thej' 

 are seen to be quietly travelling over its anatomy, or. when still, clinging to one of its hairs by means 

 of one or both of their mouth-pincers — as shown in the photo-micrograph. 



We have, therefore, on the one hand, a beetle which, apparently, is not the least incommoded 

 by what, normally considered, would be an embarrassing number of " parasites " preying upon it, 

 and on the other, a host of " parasites " which seem to possess no desire to prey upon their host. 



