Let us observe the tactics employed by the Tachina for the purpose of confiding her eggs to the Digger’s nest. It is an absolute rule that the Gnat never enters the burrow, even though she should find it open and the owner absent. The sly parasite would think twice about venturing down a passage where, being no longer free to escape, she might pay dear for her brazen effrontery. For her the one and only favourable moment for her designs, a moment awaited with exquisite patience, is that at which the Wasp dives into the gallery, with her prey clasped to her belly. At that instant, however short it may be, when the Bembex or any other Digger has half her body well within the entrance and is about to disappear underground, the Miltogramma dashes up and settles on the piece of game that projects a little way beyond the hinder extremity of the ravisher; and, while the Bembex is delayed by the difficulty of entering, the other, with unparalleled swiftness, lays an egg on the prey, or even two or three in quick succession. The hesitation of the Wasp hampered by her load lasts but the twinkling of an eye. No matter: this is long enough for the Gnat to accomplish her misdeed without allowing herself to be carried beyond the threshold. How smoothly her organs must work to adapt themselves to this instantaneous laying! The Bembex disappears, herself introducing the enemy to the home; and the Tachina goes and squats in the sun, close to the burrow, to meditate fresh deeds of darkness. If we wish to make sure that the Fly’s eggs have really been laid during this rapid manœuvre, we need only open the burrow and follow the Bembex to the bottom of her dwelling. The prey which we take from her bears at the tip of its abdomen at least one egg, sometimes more, according to the length of the delay at the entrance. These eggs are too small to belong to any but a parasite; besides, if any doubt remained, separate rearing in a box results in Fly-grubs, followed by the pupæ and lastly the Miltogrammæ themselves.