" They will be then seen in excessive
activity upon the wet earth, forming balls of mud, by rolling the
earth between their fore feet until they have manufactured each a
pill. With this they fly away to build their nest, and
immediately return for a further supply.
The arrangement of the nest is a matter of much consideration, as
the shape depends entirely upon the locality in which it is
built: it may be in the corner of a room, or in a hole in a wall,
or in the hollow of a bamboo; but wherever it is, the principle
is the same, although the shape of the nest may vary. Everything
is to be hermetically sealed.
The mason-fly commences by flattening the first pill of clay upon
the intended site (say the corner of a room); she then spreads it
in a thin layer over a surface of about two inches, and retires
for another ball of clay. This she dabs upon the plastic
foundation, and continues the apparently rude operation until
some twenty or thirty pills of clay are adhering at equal
distances. She then forms these into a number of neat
oval-shaped cells, about the size of a wren's egg, and in each
cell she deposits one egg. She then flies off in search of
spiders, which are to be laid tip in stores within the cells as
food for the young larvae, when hatched.
Now the transition from the larva to the fly takes place in the
cell, and occupies about six weeks from the time the egg is first
laid; thus, as the egg itself is not vivified for some weeks
after it is deposited, the spiders have to be preserved in a
sound and fresh state during that interval until the larva is in
such an advanced stage as to require food.
In a tropical country every one knows that a very few hours
occasion the putrefaction of all dead animal substances;
nevertheless these spiders are to be kept fresh and good, like
our tins of preserved meats, to be eaten when required.
One, two, or even three spiders, according to their size, the
mason-fly deposits in each cell, and then closes it hermetically
with clay. The spiders she has pounced upon while sunning
themselves in the centre of their delicate nets, and they are
hurried off in a panic to be converted into preserved provisions.
Each cell being closed, the whole nest is cemented over with a
thick covering of clay. In due time the young family hatch, eat
their allowance of spiders, undergo their torpid change, and
emerge from their clay mansion complete mason-flies.
Every variety of Ichneumon, however (in Ceylon), chooses the
spider as the food for its young.
