Sight could not have guided them, because, apart from the comparative rarity of this moth in that particular district, the night of their arrival was dark and stormy, his house was screened by trees and shrubs, and the female was ensconced under a gauze cover. He observed, besides, that the males did not make straight for their objective, as is characteristic of movement when directed by sight. They blundered and went astray, some of them wandering into rooms other than that in which the female was lying. They behaved, that is to say, as we ourselves do when we are trying to locate the source of a sound or a smell. But sound was ruled out by the fact that they must have been summoned from distances of a mile or a mile and a half. Olfaction remains, and with this in his mind Fabre undertook several experiments, some of which, as it happens, support, while others oppose, the theory of an olfactory cause. When the female was sequestered under the gauze cover, and in drawers or in boxes with loosely-fitting lids, the males always succeeded in discovering her. But when she was placed under a glass cover, or in a sealed receptacle, no male at all appeared. Further, Fabre found that cotton-wool stuffed into the openings and cracks of her receptacle was also sufficient to prevent the summons reaching the males. This last observation should be borne in mind in view of further discussion later on regarding the nature of the lure. Similar observations and experiments were made on the Lesser Peacock, with very much the same kind of result. But in dealing with this moth Fabre made an observation which, if it was accurate, tells against the theory of olfaction, or at least against such olfaction as we ourselves experience. At the time when he was carrying out his experiments the mistral was blowing hard from the north, and as nevertheless males arrived, they must all have come with the wind; no moth ever hatched could beat up against the mistral. But then, if the guide is an odour, the wind, blowing it to the south, would have prevented it ever reaching the males! Here, then, we have a circumstance which leaves us groping for an explanation. In watching the behaviour of the third moth on his list, the Banded Monk, on the other hand, Fabre discerned a circumstance very strongly suggestive of the operation of an odorous lure. He found that, if the female was left for a time in contact with some absorbent material and was afterwards shifted, the males were attracted, not to her new situation, but to the place where she had originally been lying. Subsequent experiment showed that a period of about half an hour was necessary to lead to the impregnation of the neighbourhood with the effluvium she elaborated.