means of the stored provender, was previously prevented from falling in. It has not been ascertained what number of eggs each insect lays, or whether it bores more than one tube, but it is presumable that it may do so, and possibly thus, from the numbers annually produced, for there are two broods in the year, colonies are thrown off which gradually form another metropolis somewhere in the vicinity, although the majority continue to occupy the old habitat from year to year. But the number of these insects is kept within due limits by the individual abundance of the parasites that infest them, and by the unsparing and unflinching attacks of earwigs, which consume all before them,—perfect insect, larva, and provender. The two most conspicuous parasites they have, are the beautiful little bee, _Epeolus variegatus_, the young of which is sustained, as in all bee-parasitism, by consuming the food stored for the sustenance of the young of the _Colletes_; and the other is the little dipterous _Miltogramma punctata_, whose larva, evolved from the egg deposited in the cell, feeds upon the larva of the _Colletes_, or possibly upon that of the _Epeolus_, which otherwise would seem to have no check to its fertility, excepting that it may be subdued by the _Forficulæ_. These insects are to be found during the spring and summer months, and throughout the southern counties, although some species are extremely local. Some occur also in the north of England and in Ireland. I am not prepared to say what flowers they prefer, for I have never captured them on flowers, but they have been found frequenting the Ragwort, and Curtis took a species at Parley Heath, in Hampshire, on the Bluebell (_Campanula glomerata_). They form a remarkable instance of an artisan bee, but so only in its habits, amongst the _Andrenides_. ------- _Two submarginal cells to the wings._ Genus 2. PROSOPIS, _Fabricius_. (Plate I. fig. 2 ♂ ♀.) MELITTA * _b_, Kirby.—HYLÆUS, Latreille.