Will crape myrtle bark scale kill my tree?

Usually not. Extension sources agree it rarely kills an established crape myrtle, but it reduces vigor, delays leaf-out, and cuts the number and size of blooms. The bigger problem is cosmetic: the scale produces copious honeydew that grows black sooty mold all over the bark, turning a showpiece tree into an eyesore.

How do I get rid of crape myrtle bark scale?

The most effective treatment is a systemic neonicotinoid (imidacloprid or dinotefuran) applied as a soil drench in spring as the tree leafs out, roughly late March through May, before bloom. Pair it with a dormant horticultural oil spray after leaf drop, and scrub the reachable bark with soapy water to remove sooty mold. Expect to re-treat every year.

When should I treat crape myrtle bark scale?

Soil-drench a systemic in spring as new growth begins, late March through May, before the tree blooms; Texas A&M research found best control from May through July. Apply dormant horticultural oil in the dormant season after leaves drop. Never apply systemics during bloom, since they can contaminate flowers that bees visit.

Is it bark scale or aphids on my crape myrtle?

Location is the tell. Bark scale makes white felt crust on the trunk and branches. Crape myrtle aphids feed on the tender new leaves at the branch tips. Both produce honeydew and black sooty mold, so sooty mold alone doesn't tell them apart. White crust on the bark means scale; sticky, curling new leaves with no bark crust means aphids.

Crape Myrtle Bark Scale: How to Spot It and Get Rid of It

Q: What is the white stuff on my crape myrtle bark?

Almost certainly crape myrtle bark scale (Acanthococcus lagerstroemiae), a felt scale that forms white or gray waxy crust on the trunk, branches, and twigs. The tell is simple: crush one of the white bumps and a live scale bleeds pink. If it bleeds pink, it's bark scale. Lichen and old sooty mold don't bleed.

If your crape myrtle’s trunk and branches are crusted with white or gray felt-like bumps, and the bark below has gone black and sooty, you have crape myrtle bark scale. It’s an Asian pest first found in a Dallas suburb in 2004, and it has spread across the South and keeps moving. This is how to identify it for certain, tell it apart from aphids, and actually treat it.

I grow crape myrtles in my zone 9 Sacramento yard, and they’re one of the best drought-tolerant flowering trees you can plant. Bark scale is the one pest that can turn them from a summer showpiece into an eyesore, so it’s worth knowing the signs even where the pest isn’t yet common.

Healthy crape myrtle in full pink bloom, the goal after treating bark scale

How to identify crape myrtle bark scale

The scale itself is tiny, about 2 millimeters, roughly the thickness of a dime. What you notice first is the effect, not the insect:

White or gray felt crust on the bark. Waxy, felt-like encrustations on the trunk, large twigs, and branches, often at branch crotches, old pruning cuts, and under loose bark. It rarely shows up on the leaves. The egg cases look like little cotton swabs.
Black sooty mold everywhere. The scale excretes copious honeydew, and black sooty mold grows on it, coating the bark, leaves, and often the grass and mulch below.
The pink bleed test. This is the one that settles it. Crush or scrape a white bump with your fingernail. A live bark scale bleeds pink, or you’ll expose a cluster of pink eggs. Clemson describes it as a reddish body fluid. If nothing bleeds pink, it’s either already dead, lichen, or old sooty mold. Nothing else on a crape myrtle bleeds pink.

The scale tends to congregate on the shadier, lower sides of branches, and crape myrtles in full sun usually carry lighter infestations. All life stages can be present on the bark year-round in warm climates, which is different from an aphid problem that comes and goes with the leaves.

Smooth, mottled crape myrtle trunk and multi-stem branches, the bark where scale forms its white crust

Look at the trunk and larger branches first, since that smooth, mottled bark is exactly where the felt crust and sooty mold show up.

Bark scale or aphids?

This is the most common mix-up, because both pests produce honeydew and black sooty mold. The difference is where the damage is:

Bark scale lives on the woody bark: trunk, branches, twigs. White felt crust is the giveaway.
Crape myrtle aphids feed on the soft new growth and leaves at the branch tips, leaving them sticky and curling, with no white crust on the bark.

If you see white specks on the bark under the black mold, it’s scale. If the bark is clean but the new leaves are sticky, it’s aphids. For the sooty mold itself, which is a symptom of either, see our sooty mold guide. And for the broader family, our guide to scale insects on trees covers the other scales you might find.

One more caution: some beneficial ladybeetle larvae (the mealybug destroyer and Scymnus species) mimic bark scale and look like little white or pink bumps. The tell is movement. Those larvae crawl around on the bark; the scale never moves. Don’t kill the moving ones, they’re eating the scale for free.

Does it kill the tree?

Healthy lavender crape myrtle in full bloom against a blue sky, the showpiece bark scale threatens

Usually not. Every extension source agrees crape myrtle bark scale rarely kills an established tree. What it does is:

Reduce the tree’s vigor and delay leaf-out in spring
Cut the number of flowers and shrink the flower clusters
Coat the whole tree, and everything under it, in black sooty mold
In heavy, long-term cases, cause premature bark peeling

So it’s mostly a cosmetic and nuisance problem, but a serious one, because the entire appeal of a crape myrtle is the smooth bark and the summer bloom, and scale ruins both.

How to treat crape myrtle bark scale

There’s no single-shot cure. The approach that works is a combination, timed to the tree’s cycle, and you should plan to repeat it annually.

1. Soil-drench a systemic insecticide (the main control)

This is the most effective treatment. A systemic neonicotinoid, either imidacloprid or dinotefuran, applied as a soil drench, moves up into the tree and kills the scale as it feeds.

Timing is everything: apply in spring as new growth begins, roughly late March through May, before the tree blooms. Texas A&M research found the best control from May through July. Rake heavy mulch away from the base, mix the product with water per the label, and pour it as a drench around the trunk. Allow several weeks for the tree to take it up.

Dose by tree size, following the label; homeowner imidacloprid products (BioAdvanced, Bonide, Fertilome, Monterey) are dosed per inch of trunk circumference. Apply only one soil systemic per year, and don’t also foliar-spray the same active ingredient. Dinotefuran is more water-soluble and generally reaches the canopy faster; imidacloprid is more widely available at retail and gives season-long control from an early-spring application.

The one hard rule: never apply a systemic during bloom. Neonicotinoids move into the flowers, where bees and other pollinators pick them up. Time it before the tree flowers.

2. Dormant horticultural oil (the winter knock-down)

After the leaves drop in fall, or in early spring before bud break, spray the trunk and branches with horticultural oil at the dormant rate, about 3 to 5 ounces per gallon. The oil smothers the exposed crawlers and nymphs. Apply when temperatures are above 45 and below 90 degrees, in the late evening, with no rain forecast for 24 hours.

Set your expectations, though: oil struggles to penetrate the waxy felt over the mature females, so don’t rely on it alone. It’s a supporting tactic that knocks down the exposed stages and helps clean the bark, not a stand-alone cure.

3. Scrub the bark (cosmetic, but satisfying)

Fresh white crape myrtle blooms on a clean stem, the look you get back once the bark is scrubbed and the scale is under control

Scrub the trunk and reachable lower limbs with a soft-bristle brush, water, and a little dish soap. This physically removes scale and the black sooty mold, and instantly improves how the tree looks. Keep the water pressure low so you don’t damage the bark.

Be clear-eyed about what this does: most of the scale is up high on twigs and branches you can’t reach, so washing is cleanup and knock-down, not eradication. It buys appearance while the systemic does the real work.

4. Protect the beneficial insects

Lady beetles, lacewings, and the mealybug destroyer all eat bark scale, and a Dallas trial found lady beetles alone gave about 75 percent suppression. They lag the scale early in the season but get strong by mid to late summer. Don’t undo their work: avoid broad-spectrum yard sprays and mosquito-fogging treatments, which kill these predators and can make a scale outbreak worse.

The last resort

If a tree is completely overrun, Clemson’s option is to cut it off flush with the ground in winter, bag or burn the wood (don’t put it in curbside brush pickup, the crawlers spread), then select three evenly spaced sprouts from the stump and grow it back. Within about three years it’s a full flowering tree again.

What not to do

Don’t treat during bloom with a systemic. Prune and time it before flowering.
Don’t stack systemics. One soil application per year.
Don’t rely on oil or washing alone. Both miss the scale that’s out of reach.
Don’t compost or curbside-dump the prunings. Double-bag infested wood or burn it, because crawlers ride the cuttings to new trees.
Don’t blanket-spray the yard. You’ll kill the lady beetles doing free work.
Don’t treat a clean tree “just in case.” Only treat a tree that actually has the pest.

Prevention

Inspect crape myrtles at the nursery before you buy, checking the bark for white felt and the pink bleed, since infested nursery stock is a main way the pest spreads. Plant in full sun where you can, since sunnier sites carry lighter infestations. And know the signs so you catch it early, when a single spring drench can stay ahead of it.

For everything else about growing these trees well, see our crape myrtle growing guide, the common crape myrtle diseases guide, and, because it’s the pest most confused with bark scale, how to get rid of aphids. Keep pruning light and correct with our crape myrtle pruning guide, since clean cuts give scale fewer places to hide.

Frequently asked questions

What is the white stuff on my crape myrtle bark? Crape myrtle bark scale. Crush a bump; if it bleeds pink, that confirms it.

Will it kill my tree? Rarely, but it cuts vigor and bloom and coats the bark in black sooty mold.

How do I get rid of it? A spring soil drench of imidacloprid or dinotefuran, plus dormant oil and bark scrubbing, repeated yearly.

When do I treat? Soil-drench in spring before bloom (late March through May); oil in the dormant season. Never during flowering.

Is it bark scale or aphids? White crust on the bark is scale; sticky new leaves with clean bark are aphids.