HYMENOPTERA 983 



on a roof, in the cavity of a large branch of sumac, in the cavity of 

 a lead pipe, and in Florida in the tubular leaves of a pitcher-plant. 



When a suitable tunnel has been made or found the bee proceeds 

 to build a thimble-shaped tube at the bottom of it. For this purpose 

 it cuts from leaves oblong pieces, each of which forms a part of a side 

 and the bottom of the thimble-shaped tube. Two such pieces had 

 been cut from the lower leaf on the left side of the spray figured here. 

 When the thimble-shaped tube is completed, the bee partially fills 

 it with a paste of pollen and honey, and then places an egg upon the 

 supply of food. She then cuts several circular pieces of leaves, the 

 diameter of which is a little greater than the diameter of the tube, 

 and forces them into the open end of it, thus making a tightly fitting 

 plug; three of these circular pieces have been cut from the spray 

 figured. Usually several cells of this kind are placed end to end in a 

 burrow; and sometimes many bees will build their nests near to- 

 gether in the same piece of wood. 



Alciddmea producta. — Among the more common members of the 

 Megachilidas is this species which builds its nests in branches of siimac 

 and other pithy plants. I have collected many of the nests during 

 winter, from which the bees emerged the following spring. A dis- 

 tinctive feature of the nest is the fact that the partitions between 

 the cells are composed of comminuted plant fibers. The larva when 

 full-grown spins a silken cocoon, which fills the cell. The adult is a 

 black bee, 7 mm. long, with white marginal bands on the abdominal 

 segments; these are often interrupted on the middle line. 



Trachiisa lateralis. — This is a parasitic species which is very com- 

 mon in the nests of Alcidamea producta. This bee is somewhat 

 smaller than its host and has on each side of the three basal abdominal 

 segments a rather small ovate yellowish -white spot. The cocoons of 

 this species are denser than those of Alcidamea producta, do not fill 

 the cell, and bear at the apex a tiny nipple. 



Other illustrations of the habits of members of this family can be 

 referred to here only briefly. 



The petals of various flowers and especially those of Pelargonium 

 often have pieces cut from them shaped like those cut from the leaves 

 of rose by the leaf-cutter bees. This is probably the work of some 

 species of Osmia, as certain European species of this genus are known 

 to build in their burrows thimble-shaped tubes resembling those of 

 the leaf-cutter bees, except that they are composed of pieces of 

 petals. 



Other species of Osmia make their cells of comminuted vegetable 

 fibers. These are placed in various situations. There are in our 

 collection several old cells of mud-wasps in each of which are several 

 cells of this kind, from which were bred a small species of Osmia. 



Some species of Osmia make use of empty shells of snails, Helix, 

 in which to build their cells, and some European species are known to 

 cover the snail shell thus used with a mound of fragments of grass 

 or of pine needles. 



