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.

It is not at all uncommon to find a gun well loaded with spiders, clay and grubs, some mason-fly having chosen the barrel for his location.

A bunch of keys will invite a settlement of one of the smaller species, who make its nest in the tube of a key, which it also fills with minute spiders.
In attacking the spider, the mason-fly his a choice of his antagonist, and he takes good care to have a preponderance of weight on his own side.

His reason for choosing this in preference to other insects for a preserved store may be that the spider is naturally juicy, plump and compact, combining advantages both for keeping and packing closely.
There are great varieties of spiders in Ceylon, one of which is of such enormous size as to resemble the Aranea avicularia of America.