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On the Metamorphosis of Qeotrupes stercorarius, L. 



By Constant Sano {i[ember of the " Wettenachajiiielijke Kiiiifj," of 

 Antwerp). Read October 14f/j, 1915. 



In early Spring the beetle may be seen flying about, especially in 

 the evening. It searches for a fresh patch of cow- or horse-dung 

 and begins to dig its nest beneath this. I found that, in the case of 

 nests just started, the female only was present, and this indicates 

 that the female makes the excavation. These nests vary very much 

 in size and form. They consist generally of a more or less vertical 

 tube, of length varying from 3 to 15cm., according to the hardness 

 of the ground (the harder the ground, the shorter the tube), and 

 then three or four horizontal branches running oft' in different 

 directions. At about 2 to 3^cm. from the vertical tube these 

 branches become somewhat broader and the extreme end is beauti- 

 fully rounded. The broad part, which constitutes the food chamber, 

 is nearly a regular cylinder, 6 to 8cm. long and 2 to 3cm. in 

 diameter; while the tube giving access to it is oval and just wide 

 enough to let the beetle pass freely carrying the food {i.e., 1^ to 

 Ifcm. wide). The sand or clay removed is brought to ihe surface 

 of the ground and put around the hole. When a food chamber is 

 prepared, the first few charges of material are taken down and put 

 at the extreme end. When 1 to l|Gm. of the chamber is filled up, 

 a little oval cavity is made and its wall strengthened by some clay. 

 The little cavity is destined to receive the egg. 



In filling up the chambers the beetle works always in the same 

 way. I several times saw, on opening already advanced nests, that 

 the male was at the top of the tube and the female at the bottom, 

 but the female was never found at the top. This indicates clearly 

 that the female arranges the food below, while the male climbs up 

 and down bringing the food to his companion. 



The egg is of a pale greenish or yellowish-white colour, and is 

 deposited in the little cavity, which is then closed, and the remain- 

 der of the food chamber is filled up with more dung till this reaches 

 the vertical tube. The female then starts another food chamber 

 from the bottom of the same vertical tube, and the process is carried 

 through till three or four eggs are laid. When an egg is just laid 

 it has a more elongated form than when it is about to hatch. It 

 has, when just laid, a length of about 8|mm. to 4mm., and a thick- 

 ness of l^mm. to Ifmm. When the date of hatching approaches 



