Just when you think everything is going gangbusters with your indoor plants, you discover mealybugs parading up and down the foliage.

You never had these critters before! Some foliage plants are discoloring, and you've never had this before! What's going on?

What you've got are mealybugs and spider mites. The reason is the lack of humidity in your home or apartment.

In the closing days of November, humidity in the house began declining. If you had a humidifier built into your heating system, you quickly turned it on. Others double-potted their indoor plants then, setting pots on trays of pebbles and water so evaporating water increased the humidity and thwarted the pests.

But what if you did nothing for your plants?

Then chances are you have the problem. Mealybugs look and behave like scales, which they are. They are about a quarter-inch long, with white, waxy body shells. Small outbreaks soon become all-out war because the female lays up to 600 eggs during her two- to three-week life. Mealybugs embed their mouths into soft leaf tissue, then siphon off the sugar the leaf needs to stay alive. These leaves discolor and fall from the plant.

Spider mites are invisible to the naked eye, but are easily detected with a 10- or 20-power magnifying glass. Check stem and trunk intersections for orange-to-pink mites, sometimes with grayish webs on leaf bottoms. Females can lay up to 200 eggs every three weeks, so populations may skyrocket.

As for getting rid of the pests, there's no need to resort to chemicals.

Gather all your indoor plants in the bathroom. Fold a large sheet of aluminum foil in half, then cut half-way through the side of the foil. With your first plant, slide the foil over the top of the pot, with the trunk of the plant at the very end of the slit made with the scissor. Fold the foil over the rim of the pot on all sides.

Work up a stream of medium hot water from the shower head in the tub, then rotate the plant sideways under the stream of water so you shower every part of the plant thoroughly. A liberal shower will dislodge any pests on stems and leaves, washing them down the drain. The foil over the top of the pot prevents water from soaking the plant. After the shower, move the plant to the dry end of the tub, remove the foil, put it on another pot and repeat. All plants that can be moved to the shower should be sprayed this way, then left overnight to absorb humidity.

Before you go to sleep, fill a few large containers with hot water, and let them stand in the tub overnight to humidify the room. Close the door so the room stays humid overnight. Next morning, return plants to their old spots.

Monster plants you can't move should be sprayed thoroughly with Safer's insecticidal soap. There are a flock of organic sprays on the market, but I urge you to stick to Safer's because of its proven record. You can buy it in ready-to-use spray or in liquid concentrate that you mix yourself. Before spraying the plants, place sheets of newspaper on the floor, several thick, to absorb the droplets that fall from the plant. Spray the Safer's liberally so the plant is dripping wet; spray limbs, stems, undersides of leaves and other plant parts.

The bugs will return if you don't raise the humidity.

Consider double-potting your plants. Think of the coffee cup and saucer. The cup is your potted plant, the saucer is a wide tray positioned below the pot. The tray should be as wide as the diameter of the plant, perhaps a bit wider.

Garden shops have trays of all materials, including decorative clay ones. Into the tray put an inch or so of pebbles or stones, also available at the garden shop. Then add water to the tray. When you are finished, the water should be below the tops of the pebbles. Rest your potted plant atop the pebbles. The moisture evaporating from the tray will raise the humidity so the bugs won't return this winter.

If you water your plant while it stands atop the pebbles, get an old basting tool from the kitchen and use it to siphon off any water that's visible in the tray. Water must always be below the tops of the pebbles.

If you don't raise the humidity immediately, plan on showering your portable plants again next weekend. You'll have to keep this up until the humidity is raised.

Other reminders for this first weekend of the New Year:

Mulch, mulch, mulch your garden now. Using shredded mulch or hardwood nuggets, lay down a liberal mulch around shrubs and trees planted last year, cuttings launched last spring, perennial flower beds, annuals like Dusty Miller that will spring to life next April, roses, herb gardens and spring bulbs planted last fall. Don't forget to renew the mulch around blueberry, blackberry, raspberry and strawberry plants; a thick mulch is your only protection against frost heave.

If you're taking down your cut Christmas tree, remember to check some branches outside the house for fireproofing. If you did things right, a branch won't burn when you hold a candle flame under the needles. Prune the limbs and use them as mulch, especially around roses. Saw the trunk into small sections, then throw the sections out.

Continue soaking the root ball of your balled evergreen everyday. You'll plant the tree next weekend.

Jack Eden hosts "Over the Garden Fence" Sundays from 10 a.m. to 1 p.m. on WTOP Radio (1500AM).