Why this species, and doubtless many others of its family, are thus favored, will soon be apparent. Ants may be seen wherever these larvæ may be found, ever ready to receive the honeyed secretion when it pleases the little creatures to eject it, but all the while exercising the closest vigilance lest some wary ichneumon may come along and deal a thrust of its ovipositor, which means misery and ultimate death to their helpless friends. So intent is the larva, with its head buried in the flower, upon its feeding, and so quietly and stealthily does the ichneumon approach its intended victim, that hardly a single individual would be left to tell the story of its existence were it not for the ants. The larvæ know their protectors, it would seem from their actions, and are able and willing to reward their services. The advantage is mutual, and the association friendly. No compelling by rough means on the one part is noticeable, and no reluctant yielding on the other. All demonstrations made by the ants are of the most gentle character. They caress, entreat, and as they drink in the sweet fluid, lifting their heads to prolong the swallowing, they manifest to the utmost their satisfaction and delight. It is amusing to see them lick away the last trace, caressing the back of the segment with their antennæ as they do so, as though they were coaxing for a little more. In Pseudargiolus the tubes are white, cylindrical, nearly equal in size, rounded at summit, and studded with little tuberculations from which arise the tentacles. These last are tapering, armed with small spurs set in whorls, and stand out straight, making a white hemispherical dome over the cylinder, but none of them fall below the plane of the base of the dome, nor do they ever hang limp or lie across the dome, as is the case in a European species. When the tube comes up the rays rise in a close pencil, and take position as the dome expands; but, on the contrary, when the tube is withdrawn, the top of the dome sinks first, the rays coming together in pencil again. [Illustration: VIOLACEA BUTTERFLY. Larva, Protected by Ants, Feeding on Flower-buds of Dogwood.]