I still ask myself in vain why these complicated manœuvres at the moment of conveying the cricket into the burrow. Why, instead of going down alone and returning to resume the prey left on the threshold, does not the Sphex drag it into the gallery, as she did in the open air, since the space is wide enough, or take it with her while she enters backwards? The various predatory Hymenoptera which I have been able to observe all drag their prey at once to the bottom of their cells, holding it underneath them by their mandibles and intermediary feet. Léon Dufour’s Cerceris does indeed somewhat complicate her movements, since after putting down her Buprestis for a moment at the door of her underground abode, she instantly goes backward into the gallery, seizes her victim with her mandibles and drags it down; but that is very unlike the tactics adopted in a like case by the Sphex. Why this domiciliary visit, which invariably precedes the introduction of the prey? May it not be that before descending hampered by a load, the Sphex thinks it prudent to give a look round the bottom of her dwelling to make sure that all is in order and to drive out, if necessary, some impertinent parasite which may have slipped in during her absence? Several Diptera, predatory flies, especially Tachinidæ, watch at the doors of all the hunting Hymenoptera, spying out the favourable moment to lay their eggs on other people’s game, but none penetrate into the dwelling, nor venture into the dark passages, where, if by ill-luck the owner caught them, they might have to pay dearly for their audacity. The Sphex, like others, pays her tribute to the predatory Tachinidæ, but they never enter her burrow to commit their misdeeds. Besides, have they not all the time they need to lay their eggs on the cricket? If they look sharp, they may very well profit by the Sphex’s momentary absence from her victim to confide their posterity to it. What yet greater danger menaces the Sphex which renders this preliminary descent to the bottom of the burrow such an imperious necessity?