The flat stone is too trifling an obstacle to disconcert the clever fly; let us find something better. I did not allow the Bembex to continue her excavation, which I saw would soon prove successful, and drove her far off with my handkerchief. The absence of the frightened insect for a considerable time allowed me to prepare my snares leisurely. What materials must now be employed? In these improvised experiments one must know how to turn all things to profit. Not far off on the high road is the fresh dropping of a beast of burden; here is wood for our arrow. The dropping was collected, crushed, and spread in a layer at least an inch thick on the threshold of the burrow and its surroundings over more than a quarter of a yard. Assuredly here was such a façade as never Bembex knew. Colour, the nature of the material, the effluvium,—all combined to deceive the Hymenopteron. Can she take this stretch of manure—this dung—for the front of the dwelling? She does! Here she comes; studying from above the unusual condition of the place, and settling in the middle of the layer, just opposite the entrance, routing about, making a way through the fibrous mass, and penetrating to the sand, she promptly discovers the mouth of the passage. I stop and drive her away a second time. Is not the precision with which the Bembex settles before her dwelling, though masked in a way so novel, a proof that sight and memory are not in such a case the only guides? What further can there be? Smell, perhaps. That is very doubtful, for the emanations from the dung could not baffle the perspicacity of the insect. Nevertheless, let us try another odour. I happen to have with me, as part of my entomological outfit, a little phial of ether. The covering of manure is swept off and replaced by a cushion of moss, not very thick, but covering a wide surface, on which I pour the contents of my phial the moment I see the Bembex coming. The over-strong emanations keep her off, but only for an instant. She alights on the moss, still reeking of ether, traverses the obstacle and penetrates to her dwelling. The etherised effluvia did not disturb her any more than did those of the manure; something surer than smell tells where her nest is.