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Plant Scale Identification & Treatment: Tips for Idaho Homeowners

If somebody told you there’s a very good chance your trees are home to tiny sap-sucking beasties with something insect experts call “piercing-sucking mouth parts,” you’d probably say, “No, they aren’t.”

Yes, they are. 

You: “No, they aren’t.”

Yes, they are.

Look, we could go back and forth about this all day, but meanwhile your trees are in danger.

So how about we move on to more important questions like “What does plant scale look like?” and “How do you get rid of plant scale?”

Because chances are, you have it.

What Exactly Are Scale?

Scale are sap-eating insects named for the scale or shell-like waxy covering that covers their bodies. 

Here In Idaho, you’ll find scale on most species of shade trees, fruit trees, and ornamental shrubs. 


Scale feed by sucking sap from trees and shrubs with their weird-sounding “piercing-sucking mouth parts.” 

What do plant scale look like? They vary in color, shape, and size, but most often appear as small, brown, rounded lumps on your plant's leaves and stems.

Two main types are pests around here:

Cottony Maple Scale

This pest is super common in Idaho.

Blame it on the popularity of the Autumn Blaze maple and its spectacular orange-red leaves. People love them. So does cottony maple scale.

Cottony Maple Scale

Their white, cottony egg masses usually contain 1,000-1,500 eggs that hatch into crawlers that suck the sap from tree cells, then move on to munch the leaves.

Quick plant scale identification tip: Severely infested trees look like they’re covered with a string of popcorn. (This sounds way more fun than it actually is.) Twigs and branches die. An infestation can kill the tree.

Pine Scale

Don’t think you have pine scale? Think again — 99 percent of pine trees in Idaho have pine scale.
You just don’t notice it. (Don’t feel bad — they’re super tiny.)

Pine Scale

What does pine scale look like? You’ll see whitish scabs on the needles of your pine tree. But these “scabs” are actually armor that covers the insect and protects it over winter. 

Meanwhile, after these pine-loving pests have happily feasted for two or three years, sucking the juice from the needles, you’ll notice your pine trees turning yellow, then brown.

How to Treat Scale on Plants

Your best defense is a one-two punch of systemic injections plus foliar treatments. 

plant health care technician spraying shrubs

Systemic insecticides injected into your trees in the spring and fall treat them from within, while spray treatments three times a year zap any bugs crawling on your trees. The foliage spray has a residual effect, too, lasting for 30 days to deter any hungry invaders.

It’s a lot easier to prevent bugs like scale than to treat them after they show up. Which brings us to….

Plant Scale Treatment: Use Dormant Oil

Also called horticultural oil, dormant oil spray is a highly refined petroleum product used as an insecticide to suffocate insects and insect eggs that have overwintered on trees and shrubs.

Instead of poisoning the scale, you’re basically smothering them with the oil. The oil kills any lingering insects as well as their eggs, so they won’t hatch in the spring. 

Timing is tricky.

Technicians start spraying trees here in Boise and Idaho Falls in early to mid-March, coating the leaves and spraying dormant oil into cracks and crevices in the bark where insects like scale have laid their eggs.

The goal for this plant scale treatment is to apply the dormant oil spray close to when trees start to bud, but before they actually bud.

If you spray too soon, it will start to wear off before the insects hatch. Apply it too late and you risk damaging the tree’s new growth.

The temperature should be at least 40 degrees, so the dormant oil spray doesn’t freeze before it dries.

Are Your Trees Ready for a New Best Friend?

Ready to rescue your precious trees from villainous hungry bugs like scale?

Tree bug treatments are available for our Idaho Falls and Boise customers who use our full-service lawn care program.

That gives you extra peace of mind — choose lawn care services in Idaho Falls, and Boise, ID that bundles your yard’s most-needed treatments into one convenient, no-fuss plan, plus know your valuable trees are protected from damaging bugs. 

Fertilizing, weed control, grub control. Done. Tree protection. Double done. 

We’ve got your back. 

Got a few minutes? That’s all you need to get started

Fill out the form on this page
Call us at (208) 656-9131.
Or read more about our services.

Then kick back and relax in your healthy, thriving yard.

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Image Source: scale, pine scale, cotton scale

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