THE BLACK REED-WASP 29 



a plug of solid mortar in the end of it, doubtless to prevent parasites 

 and ants from entering. This plug is two millimeters in thickness 

 and composed of wet, light gray clay. It dries in a few hours, harden- 

 ing into a tough cement. Next to this, a second plug, one millimeter 

 in thickness, is placed, containing more moisture than the first and 

 of a much darker shade. This is followed by a third one of the 

 same description, placed five or six millimeters in front of the second 

 plug, so that there is an air space between them which holds moisture 

 in the nest. The tube is now provisioned with small spiders of dif- 

 ferent species, varying from five to eight in number, w r hich are 

 paralyzed by the wasp's sting and brought in one by one. They are 

 packed tightly into the tube by the insect's broad head wrhich is 

 brought into use as a sort of ramrod. The tube is a tiny muzzle- 

 loader, into which she packs her living wads without mercy. 



Upon the side or apex of the last, and usually the largest, spider's 

 abdomen, she deposits a milky-white, bow-shaped egg, two milli- 

 meters in length. It is less than one-quarter as wide as long and 

 closely resembles a sausage. The spiders and the egg are now en- 

 closed in a substantial cell averaging twenty millimeters in length, by 

 the insertion of a double plug of mortar, six millimeters in thickness, 

 half of damp, dark-colored clay and half of the hard lighter material. 

 The nest is now abandoned by the parent wasps who often start imme- 

 diately to provision a second one. 



In two days the egg hatches, bringing to light a yellow-white grub 

 of thirteen segments. It commences feeding at once upon the 

 spiders, a process which may be observed under the lens as a series 

 of ripples or waves, commencing just behind the head and continuing 

 the entire length of the body, one \vave being completed or spent, 

 before the following one sets in. It grows rapidly, but very steadily, 

 increasing each day in the same ratio until the last twenty-four hours 

 of feeding, when it gains somewhat less than during the previous days. 



