Wasps, Bees, and Ants 



513 



The hairy, medium-sized mining-bees of the short-tongued genus Col- 

 letes dig short vertical burrows in the ground which they line internally with 

 a sort of slime that dries to a substance like gold-beater's skin; they partition 

 the burrow into six to ten cells in each of which is deposited an egg, together 

 with a store of food, pollen, and honey mixed. Colletes has the under- lip 

 bilobed like that of wasps and is evidently one of the lowest of the bees. 

 Prosopis is a short-tongued genus of nearly hairless, 

 small, coal-black bees which tunnel into the stems of 

 brambles and other plants, or dig burrows in the 

 ground, or make cells in crevices in walls; the cells are 

 always lined with a silken membrane, and the stored 

 food is more liquid than usual with bees. 



The dainty little blue or green carpenter-bees of the 

 long-tongued genus Ceratina are common and wide- 

 spread; their nests are tunnels in twigs and canes of 

 sumac, brambles, and other plants (Fig. 718). Corn- 

 stock writes of the nest-building of the species, C. dupla, 

 as follows: "She always selects a twig with a soft pith 

 which she excavates with her mandibles, and so makes a 

 long tunnel. Then she gathers pollen and puts it in 

 the bottom of the nest, lays an egg on it, and then 

 makes a partition out of pith chips, which serves as a 

 roof to this cell and a floor to the one above it. This 

 process she repeats until the tunnel is nearly full, then 

 she rests in the space above the last cell, and waits for 

 her children to grow up. The lower one hatches first; 

 and, after it has attained its growth, it tears down the 

 partition above it, and then waits patiently for the one 

 above to do the same. Finally, after the last one in the 

 top cell has matured, the mother leads forth her full- 

 fledged family in a flight into the sunshine. This is 

 the only case known to the writer where a solitary 

 bee watches her nest till her young mature. After 

 the last of the brood has emerged from its cell, the substance of which the 

 partitions were made, and which has been forced to the bottom of the nest 

 by the young bees when making their escape, is cleaned out by the family, 

 the old bee and the young ones all working together. Then the nest is used 

 again by one of the bees. We have collected hundreds of these nests, and, 

 by opening different nests at different seasons have gained an idea of what 

 goes on in a single nest. There are two broods each year. The mature 

 bees of the fall brood winter in the nests." 



Other familiar carpenter-bees are the great black Xylocopas (PI. XII, 



FIG. 718. Nest-tun- 

 nel of carpenter- 

 bee. (Natural size.) 



