Tim Anderson, age 10, of Eugene, Oregon, for his question:

How does the trap door spider live?

There are some 30,000 different spiders and each species leads a fascinating life of her own. Almost all of them spin fine silken threads and weave wondrous designs. Each species copies a special design inherited from her ancestors. One of the most talented spinners is the trap door spider    and her whole life is built around her elaborate weaving.

The average spider spins her web to trap the insects on which she feeds. The makeshift home, where she waits and watches, is a secret cranny near the corner of the web. But the trap door spider has other ideas. She uses her spinning talents to build a cozy home for herself and her growing children. Her silk lined burrow, with its cunning trap door, is not used to capture insect food for the family. Several species of trap door spider live in the Southwest and other warm regions of the world  ¬and each type builds her own kind of nest.

The average type is a large, dark colored spider, maybe an inch long. Though she is related to the somewhat fearsome tarantula, she is a timid creature and harmless to humans. She prefers sandy regions, where the ground is dry and diggable. The young female uses her sturdy eight legs to tunnel a burrow six to eight inches straight down into the ground. Then she weaves a delicate mesh of fine webbing to line its walls.

Her masterpiece is the trap door, which she constructs to seal the opening. First she bevels, or slopes a slight ridge around the circular opening. The door is a lid, made from a mesh of fine webbing mixed with dirt and perhaps other debris. Its sloping edge exactly fits into the beveled doorway. The final touch is a pliable hinge of silken web, attached to one side of the trap door. The outside of the door is level with the ground. The spider cunningly camouflages it with sand or dirt to match the local scenery.

This talented spider spends most of her time at home in her burrow. She opens her door a tiny crack to peek outside. When a likely insect scurries by, she darts outside to grab him. Then she dashes back inside, shuts her door and settles down to enjoy her dinner. Almost any insect will do and often she needs many to feed her family.

At least once a year, she lays a batch of perhaps 300 little round white eggs and tenderly wraps them in a silken cradle. The young spiderlings may stay with the mother for eight months. By then the burrow is very crowded. It's high time for the next generation of talented trap door spiders to leave home and go forth to make their way in the world.

Some species build burrows ten inches long. Others build a branch tunnel, sealed from the main tunnel with a second trap door. This provides a secret cradle for the eggs and a hiding place where the spiderlings can scurry in case the nest is invaded by an enemy wasp. Some build a thick, waterproof trap door that seals the burrow like a cork.