212 THE LIFE AND LOVE OF THE INSECT 



the point of emerging from the pit, go down again 

 and leave the passage free for the one who has just 

 arrived. Thanks to this mutual spirit of accommo- 

 dation, the traffic of the household proceeds without 

 impediment. 



Let us keep our eyes open. There is something 

 better than the well-preserved order of the entrances. 

 When an Halictus appears, returning from her round 

 of the flowers, we see a sort of trap-door, which closed 

 the house, suddenly fall and give a free passage. As 

 soon as the new arrival has entered, the trap rises back 

 into its place, almost level with the ground, and closes 

 the door anew. The same thing happens when the Bees 

 go out. At a request from within, the trap descends, the 

 door opens and the Bee flies away. The outlet is closed 

 forthwith. 



What can this shutter be which, descending or ascending 

 in the cylinder of the pit, after the fashion of a piston, 

 opens and closes the house at each departure and at each 

 arrival ? It is an Halictus, who has become the portress 

 of the estabhshment. With her large head, she makes 

 an impassable barrier at the top of the entrance-hail. 

 If any one belonging to the house wants to go in or out, 

 she " pulls the cord," that is to say, she withdraws to a 

 spot where the gallery widens and leaves room for two. 

 The other passes. She then at once returns to the orifice 

 and blocks it with the top of her head. Motionless, ever 

 on the look-out, she does not leave her post save to drive 

 away importunate visitors. 



Let us profit by her brief appearances outside. We 

 recognize in her an Halictus similar to the others, who 

 are now busy harvesting ; but the top of her head is bald 

 and her dress is dingy and threadbare. The handsome 



