At last she paused and laid her burden down.  Ah! the power that has led her is not a blind, mechanically perfect instinct, for she has travelled a little too far.  She must go back one row into the open space that she has already crossed, although not just at this point.  Nothing like a nest is visible to us.  The surface of the ground looks all alike, and it is with exclamations of wonder that we see our little guide lift two pellets of earth which have served as a covering to a small opening running down into the ground.

The way being thus prepared she hurries back with her wings quivering and her whole manner betokening joyful triumph at the completion of her task.  We, in the meantime, have become as much excited over the matter as she is herself.  She picks up the caterpillar, brings it to the mouth of the burrow and lays it down.  Then, backing in herself, she catches it in her mandibles and drags it out of sight, leaving us full of admiration and delight.

How clear and accurate must be the observing powers of these wonderful little creatures!  Every patch of ground must, for them, have its own character; a pebble here, a larger stone there, a trifling tuft of grass—­these must be their landmarks.  And the wonder of it is that their interest in each nest is so temporary.  A burrow is dug, provisioned and closed up, all in two or three days, and then another is made in a new place with everything to learn over again.

From this time (July thirteenth) on to the first of September our garden was full of these wasps, and they never lost their fascination for us, although owing to a decided difference between their taste and ours as to what constituted pleasant weather all our knowledge of them was gained by the sweat of our brows.  When we wished to utilize the cool hours of the morning or of the late afternoon in studying them, or thought to take advantage of a cloud which cast a grateful shade over the sun at noonday, where were our Ammophiles?  Out of sight entirely, or at best only to be seen idling about on the flowers of the onion or sorrel.  At such a time they seemed to have no mission in life and no idea of duty.  But when the air was clear and bright and the mercury rose higher and higher, all was changed.  Their favorite working hours were from eleven in the morning to three in the afternoon, and when they did work they threw their whole souls into it.  It was well that it was so, for they certainly needed all the enthusiasm and perseverance that they could muster for such wearisome and disappointing labor.  Hour after hour was passed in search, and often there was nothing to show at the end of it, for, since the caterpillars that they wanted were nocturnal species, most of them were under ground in the day-time.  The species observed by Fabre knew, by some subtle instinct, where to find the worm, and unearthed it from its burrow. Urnaria, on the contrary, never dug for her prey, but hunted on bare ground,