There's more reason to grow herbs than just being able to echance the summer salad with anise-flavored French tarragon, or livening up a stew with home-grown thyme. Herbs are almost indispensable for insect contol in the garden.

Herbs as pest controls are most effective in the small garden. Some, like mints and thyme, with spread quickly, multiplying their effectiveness. But you'll have to cub them to save room for flowers and vegetables. Don't expect miracles, but do experiment.

Garlic repels more than just vampires; it is one of the all-time handy herbs and takes up very little space. Among the bugs that hate it are aphids, borrers, Japanese beetles and mites. Rabbits don't care for it either.

Mint, rosemary and sage repel cabbage maggots as well as cabbage moths, which produce the loopers that do such damage to the cabbage family, including Brussels sprouts, broccoli, and cauliflower.

Nastursiums are not really herbs, but repel squash bugs, which lay their eggs on the undersides of leaves and multiply happily as the leaves get larger, giving the gray, diamond-shaped bugs protection and food.

White geraniums attract Japanese beetles, which, when they eat the leaves, die almost instantly. Geraniums and petunias also repel leafhoppers.

Marigolds repel nematodes, Mexican bean beetles and whiteflies.

Interplanting your asparagus bed with tomatoes is mutually advantageous; tomatoes repel asparagus beetles, and asparagus sends tomato hornworns scuttling.

Pyrethrum, widely used as the active ingredient in commercial sprays, is actully a killer plant: a killer, that is, of many insect. The perennial is a flower that looks like a daisy and can be frown from seed. Dried leaves can be used as a powder or brewed into a spray against many pests. It even works on flies.

Many herbs and flowers, and even vegetables such as hot peppers, can be transformed into insecticide sprays. In England, eight years of research showed garlic to be an alternative to DDT. It turned out to be a most successful spray in helping plants overcome not only flying and crawling pest, but many diseases and fungi. If you grow garlic for such use or as a companion planting, don't fertilize it with commmercial preparations; this reduces its effectiveness.

According to Organic Plant Protection, "take three ounces of chopped garlic bulbs and soak overnight in two teaspoons of mineral oil. Then slowly add a pint of water in which 1/4 ounce of pure soap (not detergent) has been dissolved and stir well. Strain and store in a plass or china container (garlic will react with metal). Try the spray against your worst pest, starting with a dilution of one part to 20 part to 20 parts water." You can water it down considerably more.

A mixture of hot peppers, garlic and onions, whizzed through the blender with water, is also effective.

Teas can be made from tansy, camomile or cedar chips. The tea repels just about any bug that the plant does.

A lot of experimentation is going on in home gardens with the use of organic sprays. You more or less have to try out different combinations on the come up with sinning sprays. The best book I have found on the subject is the one mentioned above, available for $12.95 from Rodale Press, Emmaus, Pennsylvania 18049. PROTECTING YOURSELF:The most effective protection I have found against bugs that attack gardeners, is vitamin B Complex. I take about 150 miligrams a half-hour before I go out and the effects last about four hours. Bugs don't like the way you smell, and you will be free of mosquito, balck-fly, deerfly and wasp bites. PABA, one of the ingredients in B-Complex, guards against sunburn. I find B-Complex effective longer than commercial repellents, besides being easier and less messy to use.

Available in nutritional or brewers yeast, B-complex, also is handy to feed pets to repel fleas and ticks, but remember it is eliminated from the system in four hours. Feeding nutritional yeast to pets works well. They like it and will eat what they need. An alternative is a couple of heaping tablespoons into their food. TOPPING TOMATOES: When tomatoes, which of course, were planted very deep to start with, have shot up eight or 10 inches, I like to add a layer of manurey straw to each plant, bringing it up around the new growth until only the top three inches or so are exposed. This promotes side-root growth that will anchor the plant when it is full of heavy fruit.