The worm "nursery" can be any old box or keg, filled with soil and plenty of leafmold to start with. It must be kept moist always, and the worms must be kept constantly supplied with vegetable matter such as grass clippings, leaves and kitchen refuse. One earthworm will have about three hundred and fifty descendants in a year's time. The progeny from this operation can be turned into the garden to condition it, or put to work pulverizing a compost pile (or go on fishing trips). It is possible to buy earthworms for such a venture. However, any energetic youngster can dig up enough worms to start a small propagating unit.
The praying mantis is an insect that a boy could cultivate as a pet (of sorts) and garden patrolman. The name of this large, pale green, sinister looking creature can be spelled either "praying" or "preying." Both words fit it. Its attitude in repose or on the alert is one of prayer, but its purpose is predatory. Its prey, fortunately, includes many insect pests, and its presence in a garden is highly desirable (if not the complete answer to the insect menace). Sometimes mantis egg masses (rounded clumps of a hardened frothy substance, yellowish-white in color) can be located on twigs of shrubs and be brought into the garden or house to hatch. It is also possible to buy them.