The Geotrupes: Nest-building 



tween them plaster the walls and increase 

 their thickness until the cavity is reduced to 

 the size needed for the hatching-chamber. 



This is the moment for laying the egg. 

 Withdrawing discreetly, the male waits with 

 materials ready to close the cell that has just 

 been filled. The closing is done by bringing 

 the edges of the sack nearer together and 

 adding a ceiling, a hermetically cemented lid. 

 This is the delicate part of the work, calling 

 for knack much more than strength. The 

 mother alone attends to it. Philemon is now 

 a mere journeyman-mason : he passes the mor- 

 tar, without being allowed on the ceihng, 

 which his brutal pressure might cause to 

 fall in. 



Soon the roof, duly thickened and rein- 

 forced, has nothing more to fear from press- 

 ure. Then the ruthless stamping begins, the 

 rough work which transfers the leading part 

 to the male. In the Stercoraceous Geotrupes 

 the difference between the sexes in size and 

 vigour is striking. Here indeed we have a 

 very exceptional case: Philemon belongs to 

 the stronger sex. He is distinguished by his 

 portly figure and muscular energy. Take 

 him in your hand and squeeze. I defy you 

 to stand it, if your skin is at all sensitive to 

 pain. With his sharp-toothed and convul- 

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