The coupling of the humble bees takes place towards the end of September. It costs the males their life, as it does with the hive bees. The impregnated females do not lay till the following spring; it is they who, after the winter is passed, will become the mothers of new generations. They will take the reins of the family when the mother who founded the colony, the males, as also the workers, shall, according to the laws of Nature, have passed away. There are often, on the other hand, some workers which, born in the spring, become fruitful, and lay the same year, but only the eggs of males. These become a butt for the jealousy of the reigning mother, who pursues them with fury, and devours their eggs. These, however, have themselves cruel hearts. Animated by a profound jealousy, they dispute the occupancy of the cells savagely, so as to be able to lay a few eggs in them, which are no sooner laid than they are destroyed by their savage sisters. However, they never make use of their stings in any of these attacks. The humble bee population is peaceful, even in its combats. After the first cold weather in autumn, all these insects, as we have said, perish, except the pregnant females. These privileged depositaries of the race, _spes altera domûs_, look for a place of retreat, and there sleep till the following spring. Then they wake up and found new colonies, which continue the race. For a long while were confounded with the humble bees certain insects which have the same appearance, that is to say, a hairy body, with bands of various colours, but whose hind legs are adapted neither for gathering honey nor for building. These are the genus _Psithyrus_: it was Lepelletier de Saint-Fargeau who discovered their true position. These are parasites, and only consist of males and fertile females, without workers. They lay their eggs in the nest of the humble bee. They are, indeed, so like their hosts, that they can introduce themselves into their dwellings without raising any suspicion. The humble bees admit them freely, and receive them as if they belonged to the family; so much so, indeed, that the poor humble bees themselves bring up the larvæ of these impudent guests. In the Order Hymenoptera one meets with many examples of these sorts of parasites, which instal their progeny in the nest of another insect, as the cuckoo does in the nests of other birds. SOLITARY BEES. We have up till now found the insects of the great family of bees collected together in perfectly organised societies. But there are a great number of species of this family which live alone. We will briefly mention the most interesting of them. The females of the solitary bees are impregnated like those of the humble bees, and lay in spring, after having passed the winter asleep. They build a nest divided into cells, fill it with eggs, and with a honied paste shut it up, and die, without having seen their progeny hatched.