Have you ever witnessed the slow death of a shrub or evergreen, and not known what was going wrong? How about a major limb on an evergreen that turned brown years ago, yet stands there like a tombstone for want of a green dye to camouflage the problem?

If this sounds familiar, you are in good company. Every summer about this time a cry goes out to take up arms against mites, those devilish, almost invisible pests that devour plants with the precision of a great white shark. Once mites gain a foothold on a shrub, you will have to spend the rest of the summer keeping them at bay. If other priorities get in the way, the mites will seize the opportunity and destroy the plant while your attention is diverted.

The problem is spruce spider mites and two-spotted spider mites. Mother's Day saw the first mites invade the garden. Their advance was slowed somewhat by the cool temperatures the last two weeks of the month; however, 90-degree readings last weekend have brought them back.

While mites are not official members of the insect family, they behave as such. Their weapons are needlelike stylets, which they insert into tissues and individual plant cells to remove life-supporting fluids. This destroys the cell and, if enough mites are feeding, usually leads to the death of the entire plant.

Mite populations on shrubs and ornamental plants begin to soar as the temperature rises. A count today would probably reveal hundreds on a large boxwood or mugho pine, but the same plant could have more than a thousand mites two weeks from now. New broods are born every few weeks, so it is very possible to have many thousands of mites destroying a massive plant by the time the July 4th weekend arrives.

Just a few of the plants attacked by mites include ajuga, arborvitae, azalea, boxwood, chrysanthemum, cotoneaster, day lily, euonymus, fir, holly, honeysuckle, hosta, ivy, pachysandra, phlox, pieris japonica, pine, primrose, privet, rhododendron, rose, spruce, viburnum and yew. In the flower garden, a thorough inspection will probably reveal small infestations of mites on many plants.

As for controls, it was commonly held that hosing down plants with a forceful stream of water would dislodge mites from foliage and needles. Unfortunately, it doesn't work. Mite populations are so high that hosing has little effect.

The best organic control is spraying superior oil on the plants every seven days from now through the third week of September -- 15 weekly applications in all. Rules to follow include spraying in the early morning, when temperatures are at their lowest, and avoiding spraying at night because of high temperatures. Also, try to spray when you can be assured that it will not rain for 24 hours after spraying.

Dormant oil should not be used, only superior oil. The products that meet the criteria are Rockland Dormant Oil and Security Dormant Oil, both of which are really superior oil.

Do not follow the winter label recommendations, or you could kill your plants. Use 1 1/2 teaspoons of superior oil to a gallon of water.

If conditions won't allow you to spray weekly, spray Kelthane (one tablespoon per gallon of water) every 10-14 days, or Orthene (three tablespoons per gallon of water) every three weeks. Spray plants well, preferably with a hand-pump sprayer.

Searing summer temperatures will soon take a toll on sunny lawns that are cut too short. If you want your lawn to survive the next three months, raise the cutting height of your lawn by adjusting the wheels of your lawnmower.

If your sunny lawn was littered with goosegrass last summer, now is the time to prevent its return. Apply Balan or Dacthal now at a bit less than the rate recommended on the label for spring crabgrass control. For example, use a setting of two for Balan on the rotary Cyclone, rotary Spyker or the drop spreader by Scott. Rain in the next week will wash the chemical into the soil and choke off any goosegrass seeds waiting to sprout.

If you had the weed last summer and decide to skip the treatment this weekend, chances are overwhelming that goosegrass will return.

A single plant yields 45,000 seeds when it reproduces in late August or early September.

As for bad news, Japanese beetles have recently moved from sunny lawns and are now feeding on bedding plants.

They will soon move onto roses, grape arbors and fruit trees.

The best way to dispense with Japanese beetles is milky spore treatment. Applied to every lawn in your neighborhood, milky spore will end these marauders for at least 15 years, possibly 20.

There is no evidence that Japanese beetles have developed a resistance to milky spore yet, therefore this remains the most economical control for the beetles.

If you work through your civic association to sign up enough homeowners, a certified applicator will treat all the homes in your neighborhood with milky spore for about $50 a home. In the absence of a neighborhood program, apply milky spore on your own.

Treat only sunny lawns. A 10-ounce container treats 2,500 square feet, the pound container treats 4,000 square feet, and the five-pound bag suffices for a half acre. Milky spore is marketed under the brand names Doom and Grub Attack.

If you are contemplating the use of beetle traps, save your dollars. University tests continue to demonstrate the ineffectiveness of the traps.

Other garden chores on the agenda:

Prune withered blossoms on rhododendron and laurel. Go down the stem below the withered flower to where the trusses connect to the main stem. Continue below this point until you find the start of new growth on opposite sides of the stem.

If you are pruning for the first time, use a sharp knife to cut through the stem a quarter-inch above the new growth. After a few stem prunings, you will have the system down pat, and you can finish up using your fingernails. Prune withered flowers now so that dormant buds can develop in late summer.

Some azaleas are still languishing with withered blossoms on the limbs. If your azaleas fit this picture, sweep away the withered flowers with a kitchen broom. Check for new growth. If you come upon short, dead limbs, take your pruning shears and go down the limb to where you find new foliage and cut at that point. If you act this weekend, the shrub will have sufficient time to recover and send out new shoots on which dormant buds can develop in late summer.

Be on the lookout for "sandwich bites" on the foliage of rhododendron and azalea. The problem is the black vine weevil, a snouty beetle that spends the day in the top inch of soil and feeds on plants at night. The weevils can be easily detected by checking the plant at night with a flashlight. The best control is Orthene (3 tablespoons per gallon of water) applied to the soil under the plant in the early evening. Repeat every 18 days through the end of July.

Gypsy moths are pupating now, so the leaf-chewing damage has ended. Trees victimized by the moths should be given a quick feeding of 10-6-4 inorganic, one pound for every inch of trunk diameter at the soil line.

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