[Illustration: FIG. 9, Larva of _Sitaris numeralis_ (Fabre, Ann. des Sci. Nat., sér. 4, tome vii.). 10, Larva of _Sitaris humeralis_, in the second stage. 11, Larva of _Sitaris humeralis_, in the third stage. 12, Larva of _Sitaris humeralis_, in the fourth stage. 13, Pupa of _Sitaris_.] The genus _Sitaris_ (a small beetle allied to Cantharis, the blister-fly, and to _Meloë_, the oil-beetle) is parasitic on a kind of Bee (Anthophora), which excavates subterranean galleries, each leading to a cell. The eggs of the _Sitaris_, which are deposited at the entrance of these galleries, are hatched at the end of September or beginning of October; and M. Fabre not unnaturally expected that the young larvæ, which are active little creatures with six serviceable legs (Fig. 9), would at once eat their way into the cells of the Anthophora. No such thing: till the month of April following they remain without leaving their birthplace, and consequently without food; nor do they in this long time change either in form or size. M. Fabre ascertained this, not only by examining the burrows of the _Anthophoras_, but also by direct observation of some young larvæ kept in captivity. In April, however, his captives at last awoke from their long lethargy, and hurried anxiously about their prisons. Naturally inferring that they were in search of food, M. Fabre supposed that this would consist either of the larvæ or pupæ of the Anthophora, or of the honey with which it stores its cell. All three were tried without success. The first two were neglected, and the larvæ, when placed on the latter, either hurried away, or perished in the attempt, being evidently unable to deal with the sticky substance. M. Fabre was in despair: “Jamais expérience,” he says, “n’a éprouvé pareille déconfiture. Larves, nymphes, cellules, miel, je vous ai tous offert; que voulez-vous donc, bestioles maudites?” The first ray of light came to him from our countryman, Newport, who ascertained that a small parasite found by Léon Dufour on one of the wild bees, and named by him Triungulinus, was, in fact, the larva of _Meloë_. The larvæ of _Sitaris_ much resembled Dufour’s Triungulinus; and acting on this hint, M. Fabre examined many specimens of Anthophora, and found on them at last the larvæ of his _Sitaris_. The males of Anthophora emerge from the pupæ sooner than the females, and M. Fabre ascertained that, as they come out of their galleries, the little _Sitaris_ larvæ fasten upon them. Not, however, for long: instinct teaches them that they are not yet in the straight path of development; and, watching their opportunity, they pass from the male to the female bee. Guided by these indications, M. Fabre examined several cells of the Anthophora: in some, the egg of the Anthophora floated by itself on the surface of the honey; in others, on the egg, as on a raft, sat the still more minute larva of the _Sitaris_. The mystery was solved. At the