THE HUNTING SPIDERS 215 



The favorite haunts of the water spider are ponds and sluggish 

 streams, in which aquatic plants are plentiful and in whose quiet 

 waters Argyroneta can best display her swimming talents. The 

 first of her underwater domiciles is built in the spring and serves 

 her well during the warmer portion of the year. In a suitable bower 

 of vegetation not far below the surface Argyroneta lays down a 

 platform of silk, suspending it by numerous attachments to ad- 

 jacent plants. The closely woven sheet and staying lines are so like 

 the water in color that they are quite invisible at first. This frame- 

 work finished, Argyroneta swims to the surface for air to provision 

 her unique home. She raises her abdomen and hind legs well above 

 the water, securing a large supply, then submerges, while the 

 brushes of long, curved hairs on her rigidly extended hind legs form 

 a screen to aid in keeping the air bubble fast beneath her body. She 

 paddles underneath the sheet and releases the air, which pushes up- 

 ward and billows the silk into a small air sac. After many trips to 

 the surface, the silk has been blown into a miniature diving bell, 

 open below, which from the outside appears as a silvery drop in 

 the water. There follows additional spinning on the bell and further 

 tieing with supporting stays to make the finished retreat a durable 

 structure. To it the spider brings fresh air as the need arises. On 

 occasion, the bell will be cut open at the top to allow air to escape, 

 after which the rent is repaired and the air renewed. 



Much of the life of the water spider is spent within the confines 

 of this underwater chamber, where feeding, molting, mating, and 

 rearing of the family all take place. Hunting goes on for the most 

 part at night, and the prey, consisting chiefly of small aquatic ani- 

 mals, is dragged into the bubble to be digested. At the time of pair- 

 ing, the male spins his smaller diving bell close to that of his mate, 

 then joins the two with a silken tunnel. At other times he will omit 

 this preliminary and swim directly to share the bell of the female. 

 Considering the cramped quarters, it is probably just as well for the 

 satisfactory conclusion of his suit that the male Argyroneta is usu- 

 ally larger than the object of his vigorous affections. 



After the mating, the eggs are laid and cradled in a tough sac 

 hung in the upper part of the bell, where they hatch after about 

 three weeks. The spiderlings move into the spacious lower portion 

 and remain there until they depart the nest. Expert swimmers from 

 the beginning and equally skilled in underwater architecture, they 

 soon fill the waters with their own tiny bubbles of quicksilver. 



In the fall Argyroneta moves into the deeper reaches of her 

 water environment and spins another domicile which will serve her 



