SOLITARY BEES. 
765 
The mason bees of the genus Osmia vary 
greatly in the manner of building their 
nests. Some make use of the stumps of 
hollow reeds, tubes, or empty snail shells, 
while others build their cells in small cav¬ 
ities in stone walls or posts. Several 
American species build earthen cells about 
half an inch in diameter which, tho rudely 
fashioned of mud on the outside, are beau¬ 
tifully polished and glazed within; In 
France, according to Fabre, the Sicilian 
Chalicodoma builds its clay cells beneath 
projecting tiles, which in the course of 
years cover five or six square yards, and 
with their great weight threaten the de¬ 
struction of the roof. (Fig. 3.) 
The observations of Fabre show that the 
mother Osmia determines the sex of her 
offspring and can lay at will either a male 
or female egg. The males of Osmia are 
much smaller than the females, and their 
cells are consequently smaller and contain 
a less amount of stores than those of the 
latter. When an old nest is used a second 
time female eggs are invariably laid in the 
large cells and male eggs in the small cells. 
Fabre induced a large number of females 
to build their cells in glass tubes of various 
sizes. When the tubes were sufficiently large 
the bees always laid first a series of female 
eggs and then male eggs. By varying the 
size of the tubes he succeeded in obtaining 
series in which the order of laying was re¬ 
versed and began with males; or in which 
the entire laying contained only males. 
“The egg, as it issues from the ovary, has 
not yet a fixed sex. The final impress that 
produces the sex is given at the moment of 
laying, or a little before.” 
The leaf-cutting bees of the genus Mega¬ 
chile build their cells of round and oval 
pieces of leaves or flower petals. They do 
not dig burrows for themselves, but make 
use of the burrows of other bees or of the 
straight tunnels of large earth-worms. If 
the shaft is longer than is needed the ap¬ 
proach from below is blocked by fragments 
of leaves piled in irregular order. After 
this barrier come five or six pockets or cells 
composed of elliptical and round sections 
of leaves which the female Megachile cuts 
out with her mandibles. The sides of the 
cell are formed of six or eight oval pieces 
in one or two overlapping rows, with the 
lower ends bent inward to form the bot¬ 
tom. Any little crevices are covered with 
small ovals to render the leaf-pot water¬ 
tight. The top of the cell is closed by two, 
three, or six, or even ten circular pieces 
which, by some marvel of geometry, are 
the exact size to fit the cell. The sections 
of leaves are taken from a great variety 
of plants, and no special preference is 
manifested for any particular species. The 
cells are provisioned with pollen and 
honey. (Fig. 3.) 
The thimble-shaped cells of the cotton 
bees of the genus Anthidium are made of 
white cottony hairs gathered from various 
kinds of thistles, mulleins, and the cotton 
rose. Only dried hairs from dead plants 
are used since hairs containing sap would 
be likely to mildew. The little packets of 
cotton, the results of many journeys, are 
felted or matted into a layer which forms 
the entire cell. So firmly are these little 
bags woven together that they may all be 
removed without separating. The cotton 
bees make use of the tunnels of Antho¬ 
phora, or the holes of earth-worms, or the 
stumps of hollow reeds. Other species of 
Anthidium employ empty snail shells, and 
are called resin bees since they divide the 
hollow spiral into cells by partitions of gum 
gathered largely from conifers, especially 
the juniper. (Fig. 3.) The economy of 
the carpenter bees is described under 
Xylocopa. 
The Anthophoridae, or cliff bees, are dis¬ 
tributed over the entire globe and are one 
of the largest bee families. The females 
of Anthophora drive tunnels six inches or 
more in length in the sides of precipitous 
cliffs, extensive colonies selecting the same 
location. In the chalk pits at Northfleet, 
England, there was a colony so large that 
in the month of April the countless num¬ 
bers assembled cast a dark flickering 
shadow on the ground. The inner walls of 
their cells are glazed with a thin cement of 
saliva applied with the tongue, which on 
hardening becomes impervious to moisture. 
An egg is laid on the surface of the stores, 
which are in a semi-liquid condition. The 
larvae pass the winter in the cells and 
change to pupae the following spring. 
Common genera are Anthophora, Melisso- 
des, and Xenoglossa. (Fig. 4.) 
