Catherine Zehner of Greenbelt asks:

What are the tiny white bugs or lice that live in the soil and attack the roots: You do not know they are there until an otherwise healthy plant starts to look wilted, or if you touch the plant the leaves fall off. When I probe the soil I can see these tiny white bugs scatter.

A. When an insect infestation is discovered it is best to isolate the affected plant so that the pest will not spread. Specific treatment is usually governed by correct identification of the pest.

Your description of the pest and the damage sounds as if your plants are infested with the ground mealy bug. This pest damages rootlets, causing plants to grow slowly and to wilt between waterings.

To control the ground mealy bug, immerse the infested plant (including the pot) in a diluted malathion solution. Put the mixture in a pail or pan large enough to accommodate the top of the largest plant to be dipped. Keep your hands out of the dipunless you are wearing rubber gloves.

Black Lear 40 (nicotine sulfate) is an alternate remedy. Soak or direnchthe soil with a solution of Black Leaf 40 in water, diluted according to directions given on the bottle.

Myrtle Van of Arlington writes:

My asparagus fern is loaded with green berries. Can I raise new plants from these berries? How should I handle them?

A. Let the seeds ripen on your asparagus sprengeri. They are red when ripe. Clean the pulp from the seed. Seed can be sown as soon as ripe or at any time of year provided the seed is kept dry and in a cool place until sown. A sowing medium of half sand and half packaged potting soil is good or use a sowing mix with which you have had success for other seeds. Moisten the mix. Plant the seed. Place the container in a transparent plastic bag to keep the mix evenly moist: set it in a bright warm place. When seedlings appear, open the bag to admit air. You can give a very diluted fertilizer solution to feed the seedlings until they are large enough to transplant into individual pots.

Newton B. Jaslow of Arlington writes:

Can you suggest some green item for a planter box that gets no (or hardly any) direct sunlight?

A. A plant for a room with only dim light is Sansevieria 'Hahni.' Hahni is a dwarf form of the familiar Sansevieria known as "mother-in-law's tongue" or "snake plant." It grows in a rosette of dark green leaves lightly banded with green and its sometimes referred to as "bird's nest." Two varieties are Golden Hahni and Silver Hahni.

This plant has a height of 4 to 6 inches anda spread of 6 to 8 inces; you may want to use three in your three-feet planter. Or you could combine it with one of the Peperomias. The veriegated blunt leaf Peperomia has light green leaves irregularly edged with white or cream; after reaching about eight or 10 inches in height it is inclined to sprawl and will fill in spaces between other plants. Emerald Ripple or Watermelon Peperomia would provide leaf-form contrast with the Sansevieria 'Hahni.'

A good and almost indestructible vining plant is Pothos (seindapsus aureus). The waxy green and yellow leaves give color in absence of flowers. A popular cultivar in the area plant shops is 'Marble Queen.' At low light levels the leaves of Pothos tend to lose their colorful markings. But when we can't have the optimal light levels, who is to scoff at a luxurious green vine?

All of these plants are adaptable to the low light levels of many of our homes and furthermore, they do well with moderate watering and average home humidity. PLANT SHOW

Answer fof Mrs. F. Halley of Arlington and several other readers who have inquired:

The National Capital Area chapter of the American Gloxinia and Gesneraid Society will hold a flower show and plant sale Oct. 8 and 9 at Tyson's Corner Center. African violets, gloxinias and other plants of this family will be on display. The show is open to the public, free of charge, from 1 to 9 p.m. on Saturday, Oct. 8, noon 4 p.m. on Sunday, Oct. 9. BOTANIC GARDEN COURSES

The U.S. Botanic Garden has again been offering free short courses for indoor gardeners. Enrollment is not necessary. The class lasts approximately one hour and will be given three times a day at 10 a.m., noon and 2 p.m. on the scheduled dates. Classes are held at the Botanic Garden Conservatory, First street and Maryland Avenue SW. For additional information call 225-7040. The course now being offered is:

Flowering Houseplants - Care of several popular flowering houseplants, such as bromeliads, gardenias and geraniums. A demonstration on foreing bulbs for indoor decoration will be included, Saturday, Oct. 22 through Saturday, Oct. 29. Instructor, Garden Staff member. ORCHID SHOW

The annual show of the National Capital Orchid Society is scheduled for Oct. 8, 9 and 10 at the U.S. National Arboretum, 24th and R Street NW. The show is free and open to the public from 1 to 6 p.m., Saturday, Oct. 8; from 10 a.m. to 6 p.m., Sunday, Oct. 9; and from 10 a.m. to 5 p.m., Monday, Oct. 10. FERN SHOW

A display of 100 different ferns and a special fern garden will be open to the public from Oct. 8 to 16 at Great Falls Greenhouses. 10106 Georgetown Pike, Great Falls, Va. Hours are 9 a.m. to 5 p.m. week days, and 11 a.m. to 5 p.m. on Sunday. Ferns and other plants will be available for purchase.