I suspect that the Necrophorus, without any prevision of the consequences of his action, heaved his back simply because he felt the legs of the creature above him.

With the system of suspension adopted, the push of the back, employed in all cases of difficulty, was brought to bear first upon the point of support; and the fall resulted from this happy coincidence.

That point, which has to be slipped along the peg in order to unhook the object, ought really to be situated at a short distance from the Mouse, so that the Necrophori shall no longer feel her directly against their backs when they push.
A piece of wire binds together now the tarsi of a Sparrow, now the heels of a Mouse and is bent, at a distance of three-quarters of an inch or so, into a little ring, which slips very loosely over one of the prongs of the fork, a short, almost horizontal prong.

To make the hanging body fall, the slightest thrust upon this ring is sufficient; and, owing to its projection from the peg, it lends itself excellently to the insect's methods.

In short, the arrangement is the same as it was just now, with this difference, that the point of support is at a short distance from the suspended animal.
My trick, simple though it be, is fully successful.