The larvae of the various dung-beetles utilise their alimentary residues in rough-casting their houses, which by their dimensions lend themselves to this method of disposal, while evading the necessity of opening temporary windows by which the ordure can be expelled. Whether for lack of sufficient room, or for other reasons which escape me, the larva of the Sisyphus, having employed a certain amount in the smoothing of the interior, ejects the rest of its digestive products from its dwelling.
Let us examine one of these “pears” when the inmate is already partly grown. Sooner or later we shall see a spot of moisture appear at some point on the surface; the wall softens, becomes thinner, and then, through the softened shell, a jet of dark green excreta rises and falls back upon itself in corkscrew convolutions. One excrescence the more has been formed; as it dries it becomes black.
What has occurred? The larva has opened a temporary breach in the wall of its shell; and through this orifice, in which a slight thickness of the outer glaze still remains, it has expelled the excess of mortar which it could not employ within. This practice of forming oubliettes in the shell of its prison does not endanger the grub, as they are immediately closed, and hermetically sealed by the base of the jet, which is compressed as by a stroke of a trowel. The stopper is so quickly put in place that the contents remain moist in spite of the frequent breaches made in the shell of the “pear.” There is no danger of an influx of the dry outer air.
The Sisyphus seems to be aware of the peril which later on, in the dog-days, will threaten its “pear,” small as it is, and so near the surface of the ground. It is extremely precocious. It labours in April and May when the air is mild. In the first fortnight of July, before the terrible dog-days have arrived, the members of its family break their shells and set forth in search of the heap of droppings which will furnish them with food and lodging during the fierce days of summer. Then come the short but pleasant days of autumn, the retreat underground and the winter torpor, the awakening of spring, and finally the cycle is closed by the festival of pellet-making.
One word more as to the fertility of the Sisyphus. My six couples under the wire-gauze cover furnished me with fifty-seven inhabited pellets. This gives an average of more than nine to each couple; a figure which the Scarabaeus sacer is far from attaining. To what should we attribute this superior fertility? I can only see one cause: the fact that the male works as valiantly as the female. Family cares too great for the strength of one are not too heavy when there are two to support them.
A BEE-HUNTER: THE PHILANTHUS AVIPORUS