What would be the use of sight underground?
The eyes of the larvae leaving their burrows are black and shining, and evidently capable of sight.

When it issues into the sunlight the future Cigale must find, often at some distance from its burrow, a suitable twig from which to hang during its metamorphosis, so that sight is obviously of the greatest utility.

The maturity of the eyes, attained during the time of preparation before deliverance, proves that the larva, far from boring its tunnel in haste, has spent a long time labouring at it.
What else do we notice?
The blind, pale larva is far more voluminous than in the mature state; it is swollen with liquid as though it had dropsy.

Taken in the fingers, a limpid serum oozes from the hinder part of the body, which moistens the whole surface.

Is this fluid, evacuated by the intestine, a product of urinary secretion--simply the contents of a stomach nourished entirely upon sap?
I will not attempt to decide, but for convenience will content myself with calling it urine.
Well, this fountain of urine is the key to the enigma.