THE NET-MAKING CADDIS WORM 



larva, as typical of all others. It had found refuge, 

 after much wandering, against one side of a water- 

 logged bit of wood, one end of which rested against a 

 pebble as big as a filbert. The chip was so shaped that 

 it sloped upward from the bottom, forming a projec- 

 tion like the eaves of a roof. A number of sand pellets 

 as large as rice grains, and some as big as a pea, lay 

 beside it. 



The larva began work by clearing away the sand in 

 the angle formed by the chip where it rested against the 

 pebble and made a snug corner that promised to be the 

 nucleus of a den. It bored into the underlying sand 

 until a small cavity was formed, almost large enough to 

 contain its body. Then it turned to the pellets in front. 

 It moved its jaws — the under part of its head — many 

 times over them, smearing them with a viscid secretion 

 from its silk glands. The pieces were thus glued to- 

 gether in a loose bunch, and, ere one could make out 

 exactly the process, were lifted and "butted" up against 

 the pebble buttress. There they dangled, in the fashion 

 of a bead necklace, and formed the beginning of a wall 

 that was planned to enclose the angle made by the up- 

 ward slant of the chip. When the wall was formed (by 

 the same method) a circular space was cleared away 

 near its union with the pebble, apparently the beginning 

 of a tubular case of which this would be the door. The 

 chief instruments in these acts were the head and fore 

 paws; but undulatory movements of the body, kept up 

 with almost rhythmic regularity, seemed to be effective 

 in shaping the interior space and the general line of the 

 wall. 



While thus engaged, the little architect would now 

 and then be lost to sight. But the agitation of the 



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