The genus _Eucera_ appears in May and June. In some parts they are found in large colonies; although I have seen them abundant I never found them in this gregarious condition, and I have usually discovered them frequenting loamy and sandy soils; they burrow a cell six or eight inches deep, form an oval chamber at its extremity, which as well as the sides of the cylinder leading to it they make extremely smooth, and by some process prevent its absorbing the mixture of honey and pollen which they store for the supply of the larva, and each contains but one young one. These, having full fed, lie in a dormant state throughout the winter and do not change into pupæ until mid-spring, and speedily transform into the imago, which, until fully matured, is closely in every part and limb covered with a thin silky pellicle, wherein it lies as in a shroud, but at its appointed time, regulated by some influence of which we have no cognizance, active life becomes developed, it then casts off its envelope and comes forth to revel in the sunshine, in close companionship with a partner which its instinct promptly teaches it to find. The largest of our native _Nomadæ_ is its parasite the _N. sexcincta_, and which seems wholly restricted to it, but which is often even rare in places where the _Eucera_ abounds. The female, like those of the rest of the bees, is no time-waster, but flies steadily to and fro in her occupation of provisioning her nest, and the male often accompanies her in these expeditions, gallantly winging about with extreme velocity as if to divert his sedulous companion in the fatigue of her toil, by his evolutions and his music, which is very sonorous. And on a fine May day it is extremely pleasant in a picturesque situation to sit and watch the operations of these very active insects. In their recent state, when just evolved from the nidus, they are very elegant, being covered with a close silky down, which labour and exposure soon abrades. It is said that this bee deserts her nest when she finds the stranger’s egg deposited on the provender laid up in store, or when she meets with the _Nomada_ within, which sometimes lays two eggs in one cell. To this she does not deliver battle, as does the _Anthophora_ to _Melecta_, but patiently vacates the nest, leaving it to the service of the parasite, which is also supposed to close it herself, having been caught with clay encrusted upon her posterior legs. For the accuracy of this supposition I cannot vouch, never having observed the circumstance, nor have I seen reason to abandon the idea that the parasite has no instinct for labour of any kind,—the presence of the clay being, I expect, merely accidental, for it is notorious that these insects have an overruling predilection for keeping themselves extremely clean.