28 



at the time of disclosure, lies on its back and moves continuously 

 the legs and abdomen. The skin splits just behind the head and 

 slips over this towards the mouth and goes backwards over the 

 ventral part. As the skin comes along it carries with it the white, 

 silverlike lining of the trachese. When the beetle is completely 

 free from the skin, it turns over on its ventral side and lifts up the 

 elytra, which, together with the abdomen and underside of thorax, 

 are completely white. Then slowly it stretches out simultaneously 

 the two wings. After a couple of hours the white parts, except the 

 membranes knitting the abdominal segments, become darker, and 

 after five oi* six hours are all black with metallic reflection, except 

 the second pair of wings, which are brownish and transparent, and 

 are folded away below the elytra. The beetle is very shiny and 

 looks as if wet, but after a while this lustre disappears and the beetle 

 becomes duller. When coming to the surface the beetle does not 

 always use the original tube made by the parent to take the food 

 down, but works itself up displacing behind it the remaining food 

 and the earth through which it passes. 



The beetle is of a dark blue-black colour with metallic reflection, 

 especially on the undersides. The female is, on an average, slightly 

 larger than the male, but the difference is only very slight. The 

 male can be distinguished from the female in having on the posterior 

 trochanters and femora two equally sized teeth, while the female has 

 none. Both sexes are able to produce a rather distinct noise by 

 rubbing the abdomen against the hind femora. 



When the perfect beetle has emerged at the end of the summer 

 it comes to the surface for feeding purposes, afterwards it digs a 

 tube in which it will pass the winter. In the following spring it 

 conies again to the surface and starts egg-laying. 



EXPLANATION OF PLATE V. 

 Metamorphoses of Geotrupes stercorarius, L. (all natural size) 



1. Egg in food mass. 



2. Yonng larva just hatched, and empty egg-skin. 



3. Full-grown larva in pupation chamber. 



4. Larva in pupation chamber awaiting pupation. 



5. Pupa just after disclosure. 



6. Pupa just before liberation of the beetle. 



