of smooth pebbles no longer visited by the waters. Lastly, if a cobble
be wanting, the Mason-bee will establish her nest on any sort of
stone, on a mile-stone or a boundary-wall.

The Sicilian Chalicodoma has an even greater variety of choice. Her
most cherished site is the lower surface of the projecting tiles of a
roof. There is not a cottage in the fields, however small, but
shelters her nests under the eaves. Here, each spring, she settles in
populous colonies, whose masonry, handed down from one generation to
the next and enlarged year by year, ends by covering considerable
surfaces. I have seen some of these nests, under the tiles of a shed,
spreading over an area of five or six square yards. When the colony
was hard at work, the busy, buzzing crowd was enough to make one
giddy. The under side of a balcony also pleases the Mason-bee, as does
the embrasure of a disused window, especially if it is closed by a
blind whose slats allow her a free passage. But these are popular
resorts, where hundreds and thousands of workers labour, each for
herself. If she be alone, which happens pretty often, the Sicilian
Mason-bee instals herself in the first little nook handy, provided
that it supplies a solid foundation and warmth. As for the nature of
this foundation, she does not seem to mind. I have seen her build on
the bare stone, on bricks, on the wood of a shutter and even on the
window-panes of a shed. One thing only does not suit her: the plaster
of our houses. She is as prudent as her kinswoman and would fear the
ruin of her cells, if she entrusted them to a support which might
possibly fall.

Lastly, for reasons which I am still unable to explain to my own
satisfaction, the Sicilian Mason-bee often changes the position of her
building entirely, turning her heavy house of clay, which would seem