THE NESTING OF A LEAF-CUTTING BEE. 



{Megachile sapellonis.} 



Almost every garden shows evidence 

 of the work of leaf-cutting bees, for the 

 Megachiles are very numerous, and per- 

 haps the most widely distributed of the 

 wild bees. They may be found in every 

 continent and even in the Sandwich Isl- 

 ands. How they have spread over the 

 earth and reached even the far-away 

 oceanic islands would be another prob- 

 lem for Sherlock Holmes or a naturalist 

 with the same keenness' and zeal. There 

 they are in every garden in the land, 

 leaving their marks by cutting circular 

 pieces from the leaves, as smoothly and 

 deftly as though fairies' scissors had 

 been used. 



The nests of the Megachiles are fine 

 bits of architecture. It is said that 

 some species of the genus select holes 

 made by beetle larvae or other insects, 

 and I saw a bee of this genus building in 

 mud cells under a rock. But the Sapello 

 Megachile is a true carpenter and makes 

 its nest in fallen logs or tree stumps, cut- 

 ting out its tunnel just as carefully and 

 on much the same plan as that used by 

 the Clisodon. The chief difference in 

 this part of the work is that no sawdust 

 is preserved but is kept flying about as 

 though in a small hurricane, as the bee 

 cuts away with her strong sharp mandi- 

 bles. 



When the tunnel is finished and 

 cleaned the cells are made. These con- 

 form to the shape already marked in the 

 excavation, and look much like a child's 

 thimble though they are slightly broader 

 at the bottom than at the top. The cells 

 are made from pieces cut from the leaflets 

 of the wild rose, which grows in such 



luxuriance in the canyon. The roughly 

 circular pieces are nearly a fourth of an 

 inch across and twenty or more pieces 

 are used in forming each cell, carefully 

 arranged in rows and fastened together 

 by a gummy substance. 



The cell when finished is half filled 

 with pollen, which the bee gathers from 

 the flowers which are abundant indeed 

 at the mid-summer season, the time when 

 the bee nests. The pollen mass in the 

 cell is quite different from that provided 

 by the other bees, whose nests I have 

 studied; for it is dry and odorless and 

 when examined under the microscope 

 shows the characteristic shapes of the 

 pollen grains — tiny footballs, green and 

 yellow lay among spiked yellow globes 

 and light green crescents. 



The egg is placed on top of this food- 

 mass, a rose leaf lid is firmly glued to 

 the top of the cell, and if no parasite has 

 placed its egg in the cell during the 

 Megachile's absence, the young bee has 

 a safe and comfortable place in which to 

 pass its youth. 



As is seen from the pollen in the nest, 

 the Megachile visits many different flow- 

 ers, but it does not fly first to one species 

 and then to another, but visits many 

 flowers of the same sort, a marvelous 

 adaptation which aids in the develop- 

 ment of the plants. The legs are with- 

 out the baskets of the bumble-bee and 

 are covered with short rather sparse 

 hairs, but the pollen is carried in the 

 branched hairs under the abdomen, 

 which are thick and long, making an ad- 

 mirable arrangement for holding pollen. 



WlLMATTE COCKERELL. 



68 



