Crape Myrtle Bark Scale: Identification and Treatment

Walk up to the tree and look at the trunk. White patches, like somebody flicked paint on the bark. Gray felt in the branch crotches. And everything under the tree, the patio, the car, the mulch, coated in black. That is crape myrtle bark scale, and it is practically a North Texas native at this point. It was first found in the United States right here in Texas, back in 2004, and it has been working its way through every crape myrtle in the region since.

How to tell it is bark scale

The signature is the white to gray felt-like crust on the bark. Trunk, limbs, twigs, branch crotches. It looks like whitewash splatter or lint stuck to the tree. In spring the crawlers, the young mobile stage, are tiny and pinkish if you look close. What most people notice first is not the insect at all. It is the black.

Scale insects feed on sap and excrete honeydew, a sticky sugar water. Honeydew grows sooty mold, a black fungus that coats the bark and rains down on everything beneath the canopy. A badly infested crape myrtle looks like it was in a fire. Blooming drops off, sometimes to almost nothing, and over a few years the branches start dying back from the tips.

Two things it is not. Lichen, the flat gray-green crusty patches on old bark, is harmless and not an insect. And plain dirt or algae washes off. Bark scale felt does not rinse away with a casual hose-down, and it comes back if you only wash the sooty mold without treating the insect.

Why North Texas gets it worst

Crape myrtles are the default small tree of North Texas. Every subdivision, every commercial strip, every other front yard. That is a lot of host material packed close together, and bark scale moves on wind, on birds, and on nursery stock. Mild winters mean more scales survive to spring. Once one tree on the street has it, the neighbors usually follow within a season or two.

Stressed trees get hit harder. Crape myrtles baking in reflected heat off a parking lot, trees topped into knuckles every spring, trees fighting drought, all of them carry heavier infestations than a healthy tree in good soil. If your crape myrtles have been topped year after year, the weak regrowth is prime scale habitat.

Treatment that actually works

There is no one-spray fix, but the combination below controls it. Do all of it, not just the easy part.

Wash and scrub the bark. A soft brush with soapy water, or a pressure washer on a low, wide setting, knocks the felt masses off the trunk and limbs. This does not kill every scale, but it removes the protective covering and the sooty mold, which exposes the insects underneath to everything else you do. Do this first, any time of year you see the white crust.

Dormant oil in late winter. Horticultural oil sprayed while the tree is leafless smothers the overwintering scales. Late winter, before bud break, is the prime window. Coat the trunk and limbs thoroughly. This is the single highest-value spray timing for bark scale.

Systemic insecticide in spring. Soil-applied systemics move up through the tree and kill the scales as they feed. Texas A&M trials found dinotefuran drenches the fastest-acting option, with imidacloprid also effective but slower. Apply in spring ahead of the growing season, and follow the product label exactly, rates, timing, and pollinator precautions. Crape myrtles bloom in summer and bees work the flowers, so label timing matters.

Prune out the worst of it. Branches that are heavily crusted and dying back should come off. Cut back to healthy wood with proper pruning cuts, our trimming page shows the three-cut method, and bag the debris. Do not compost infested prunings or chip them into mulch you spread around clean trees.

Ease off the fertilizer. Heavy nitrogen pushes soft, sappy growth that scale insects love. If you have been feeding the crape myrtle hard every spring, back off while you are treating.

Lady beetles and other predators do eat bark scale, and you will see them working infested trees. They help. They will not control an infestation by themselves, so do not wait on nature to finish the job.

What does not work

Topping the tree. Cutting a crape myrtle back to knuckles does not remove bark scale, and the flush of weak regrowth gives the next generation fresh feeding ground. If the tree has been topped for years, the right move is selective thinning back to a natural form, not another hard cut.

Ignoring it. Bark scale does not go away on its own, and the sooty mold spreads to the patio, the fence, the car, and the plants underneath. A two-year infestation is a weekend project. A five-year infestation is a tree you are thinking about removing.

Spraying the sooty mold. The black coating is a fungus growing on honeydew. Killing the fungus without killing the scale is mopping the floor with the faucet running.

Prevention for the rest of your trees

Check every crape myrtle on the property, not just the ugly one. Early infestations are a few white flecks in a branch crotch, easy to scrub off and treat before the black starts. When you buy new crape myrtles, inspect the bark at the nursery and do not bring home infested stock. Give trees air flow and sun rather than crowding them against the fence, and keep them watered through drought so they are not stressed. Our drought-watering guide covers the deep-soak method.

Bark scale is beatable. It just takes the full program: scrub, dormant oil, a labeled systemic, prune the worst, and patience for a season. The blooms come back.

Common Questions