It is almost certain that some of these, usually a trifle smaller than the honeybees, are andrenas or mining bees. There are about 200 different kinds of Andrena in Europe alone. One of my favorites is A. armata, a species very common in England, where it is sometimes referred to as the lawn bee. The females like to burrow in the short turf of well-kept lawns, where their little mounds of earth often appear by the hundreds. Almost equal in size to a honeybee. A. armata is much more beautiful in color, at least in the female of the species: a rich, velvety, rusty red. The males are much duller.

After having mated, an Andrena female digs a hole straight down into the ground, forming a burrow about the size of a lead pencil. The bottom part of a burrow has a number of side tunnels or ``cells,'' each of which is provided with an egg plus a store of beebread. The development of the Andrena larvae is very rapid, so that by the end of spring they have already pupated and become adults. But they are still enclosed in their larval cells and remain there throughout the summer, fall, and winter. Their appearance, next spring, coincides in an almost uncanny way with the flowering of their host plants. In the Sacramento valley in California, for instance, it has been observed that there was not one day's difference between the emergence of the andrenas and the opening of the willow catkins. This must be due to a completely identical response to the weather, in the plant and the animal.