The parasites of the Humble bee are numerous. Such are the species of Apathus, which so closely resembles the Humble bee itself, that it requires long study to distinguish it readily. Its habits are not known, other than that it is found in the nests of its host. It differs from the Humble bee in having no pollen-basket, showing that its larvae must feed on the food stored up by their host, as it does not itself collect it. The mandibles also are not, like those of Bombus, trowel-shaped for architectural purposes, but acutely triangular, and are probably not used in building. The caterpillars of various moths consume the honey and waxen cells; the two-winged flies, Volucella and Conops, and the larvae of what is either an Anthomyia or Tachina-like fly, and several species of another genus of flies, Anthrax, together with several beetles, such as the Meloe (Fig. 16), Stylops (Fig. 17, male; 18_b_, female; _a_, position in the body of its host), and Antherophagus prey upon them. [Illustration: 17. Male Stylops.] The power of boring the most symmetrical tunnels in solid wood reaches its perfection in the large Virginian Carpenter bee (Xylocopa Virginica, Fig. 19). This bee is as large as, and some allied exotic species are often considerably larger than, the Humble bee, but not clothed with such dense hairs. We have received from Mr. James Angus, of West Farms, N. Y., a piece of trellis from a grape vine, made of pine wood, containing the cells and young in various stages of growth, together with the larvae and chrysalids of Anthrax sinuosa (Fig. 20), a species of fly parasitic on the larva. The maggot buries its head in the soft body of the young bee and feeds on its juices. Mr. Angus thus writes us regarding its habits, under date of July 19: "I asked an intelligent and observing carpenter yesterday, if he knew how long it took the Xylocopa to bore her tunnel. He said he thought she bored about one-quarter of an inch a day. I don't think myself she bores more than one-half inch, if she does that. If I mistake not, it takes her about two days to make her own length at the first start; but this being across the grain of the wood, may not be so easily done as the remainder, which runs parallel with it. She always follows the grain of the wood, with the exception of the entrance, which is about her own length. The tunnels run from one to one and a half feet in length. They generally run in opposite directions from the opening, and sometimes other galleries are run, one directly above the other, using the same opening. I think they only make new tunnels when old ones are not to be found, and that the same tunnels are used for many years. Some of the old tunnels are very wide. I have found parts of them about an inch in diameter. I think this is caused by rasping off the sides to procure the necessary material for constructing their cells. The partitions are composed of wood raspings, and some sticky fluid, probably saliva, to make them adhere.