Another species of this large genus, _Crabro luteipalpis_, is fond of making its burrows in the mortar of old walls, preferring those spots where nails have been drawn, making the process of burrowing easier for the insect. It is not uncommon in the outskirts of London. All gardeners, especially those who cultivate roses, ought to encourage this very little insect, and welcome its presence, for it provisions its nest with the aphides, or green blight, which infect the rose-trees, and which have destroyed so many promising plants. The female, which is the larger of the two sexes, measures only three lines in length. The colour is shining black, and the head is rather squared. Among other burrowing species of this genus we may mention _Crabro varius_, a rather long and slender insect, black in colour, with yellow spottings about the thorax. It prefers very hard fine sand, such as is found in partially excavated sand-banks, and provisions its burrows with gnats. It is tolerably plentiful. Our last example of the earth-burrowers belonging to this genus is _Crabro Wesmoeli_, which chooses similar localities, being mostly found in sand-banks. It carries off flies of different kinds for the food of its young. There is a very common insect, closely allied to the last mentioned genus, whose horns are worthy of notice. This is called _Typoxylon figulus_. It is a small creature, with a large head and slender abdomen. Its colour is black, and on the edges of the segments of the abdomen there is a little silvery shining down. It generally burrows into light earth, though it sometimes drives its tunnel into decayed wood. In either case, it provisions its nest with spiders, flying into the hedges, pulling the unfortunate spiders out of their webs, and carrying them into the burrow. One burrow contains a series of cells, which are separated from each other by partitions of sand, the particles of which are firmly cemented together by some glutinous substance secreted by the insect. Some species of this genus burrow into the pith of the bramble and other shrubs. One of the most determined of our British burrowers is the insect which is known by the name of _Ammophila sabulosa_. It has a large, squared head, wider than the thorax, a very long and slender body, and short though powerful wings. The colour is black, with a slight rust-red tint on the base of the abdomen.