Hosts, like Boy Scouts, should Be Prepared.

Not only do guests drop in with no notice, once there they fix you with a lean and hungry look until food is forthcoming.

But what food? Help in figuring that out comes from a surprising source, the U.S. Government Printing Office, where amid economic surveys and statistical reports there are booklets on food.

Cheese and crackers are the all-time standby, but to get away from the Brie cliche, buy a copy of "Cheese Varieties and Descriptions" (Agriculture Handbook No. 54, $2.75). A 151-page book which Craig Claiborne calls the best reference on cheeses, it starts with Bohemia's Abertam and ends up at Turkey's Zomma, describing cheeses and how they're made.

For instance, "Fontina is a cooked-curd, whole-milk, semi-soft to hard, slightly yellow cheese with a delicate, nutty flavor and a pleasing aroma. It is made from ewe's milk in the Aosta Valley in Piedmont, Italy. (It is said to be made also from cow's milk in the United States.) . . ." etc.

Or, "Tworog, a sour-milk cheese, is made on a large scale by Russian farmers. The milk is set in a warm place for 24 hours; then the whey is removed and the curd is put into wooden forms and pressed. The cheese is often used in making a bread called Notruschki."

"Storing Perishable Foods in the Home" (Home and Garden Bulletin No. 78, $1.25) gives information on how long various foods can be stored and how to keep them. Did you know eggs are best eaten within a week of buying them? Or that you shouldn't wash asparagus putting it in the refrigerator?

Another drop-in special is the bowl of salted nuts. "Nuts in Family Meals" (Home and Garden Bulletin No. 176, 35 cents) advises on the difference in storage life between shelled and unshelled nuts, the best way to shell them and how much you need in unshelled nuts to get so many ounces or cups of nut meats.

For the old freezer fall-back, "Home Freezing of Fruits and Vegetables" (Home and Garden Bulletin No. 10, $1.30) explains, among other things, why it is necessary to blanch vegetables before freezing them.

The blandest cheese or tinned pate tastes better when served with homemade pickles or chutney. "Making Pickles and Relishes at Home" (Home and Garden Bulletin No. 92, $1.15) reveals the mysteries of pickling, with recipes for things like Watermelon Pickles and Tomato-Pear Chutney. There is a handy section in the back which tells Why Things Went Wrong.

Handy for when your guests -- or your cup -- runneth over is "Removing Stains From Fabrics" (Home and Garden Bulletin No. 62, $1.20) which will tell you how to get candlewax out of granny's damask tablecloth and make gravy stains and wine splotches disappear.

The booklets can be purchased at one of the local GPO bookstores, or by sending a check to the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.