Harry Randolph, age 9, of Decatur, I11., for his question:

WHAT IS A PACK RAT?

When a person collects and saves all sorts of useless junk, we  sometimes call him a "pack rat." We get this name from the pack rat, a native North and Central American that is also sometimes called the wood or the trade rat.

The pack rat looks much like a house rat, but has softer fur and a hairy, instead of a naked, scaly tail. The pack rat also has cleaner habits. It will not live in sewers and garbage dumps.

Pack rats are curious about everything that goes on around them. They pick up and hide or carry home small articles that catch their fancy, such as silverware, nails, buckles and even brightly colored stones.

Sometimes the rat will drop and leave behind something he is carrying, in order to "pack off" a more attractive article. This accounts for its also being called a trade rat.

Some western pack rats live in the mountains and build their nests on rock ledges. Others live on the deserts in clumps of cactus and scrubby grass.

A female pack rat will have one or two litters of three to six young each season.