lie in wait for the passing game. In nooks which they repair in
summary fashion with earthen embankments or clay partitions, Hunting
Wasps--Pompili and Tripoxyla--store up small members of the Spider
tribe, including sometimes the Weaving Spiders who live in the same
ruins.

I have said nothing yet of the Chalicodoma of the Shrubs. My silence
is not due to negligence, but to the circumstance that I am almost
destitute of facts relating to her parasites. Of the many nests which
I have opened in order to study their inhabitants, only one so far has
been invaded by strangers. This nest, the size of a large walnut, was
fixed on a pomegranate-branch. It comprised eight cells, of which seven
were occupied by the Chalicodoma, and the eighth by a little Chalcis,
the plague of a whole host of the Bee-tribe. Apart from this instance,
which was not a very serious case, I have seen nothing. In those
aerial nests, swinging at the end of a twig, not a Dioxys, a Stelis,
an Anthrax, a Leucopsis, those dread ravagers of the other two Masons;
never any Osmiae, Megachiles or Anthidia, those lodgers in the old
buildings.

The absence of the latter is easily explained. The Chalicodoma's masonry
does not last long on its frail support. The winter winds, when the
shelter of the foliage has disappeared, must easily break the twig,
which is little thicker than a straw and liable to give way by reason of
its heavy burden. Threatened with an early fall, if it is not already on
the ground, last year's dwelling is not restored to serve the needs of
the present generation. The same nest does not serve twice; and this
does away with the Osmiae and with their rivals in the art of utilizing
old cells.

The elucidation of this point does not remove the obscurity of the next.
I can see nothing to account for the absence or at least the extreme
rareness of usurpers of provisions and consumers of grubs, both of whom
are very indifferent to the new or old conditions of the nest, so long
as the cells are well stocked. Can it be that the lofty position of the
edifice and the shaky support of the twig arouse distrust in the Dioxys
and other malefactors? For lack of a better explanation, I will leave it
at that.

If my idea is not an empty fancy, we must admit that the Chalicodoma of
the Shrubs was singularly well-inspired in building in mid-air. You have
seen of what misfortunes the other two are victims. If I take a census
of the population of a tile,