Tree problems · Insect
Scale insects: signs and what to do
Scale insects is an insect pest, often seen on crape myrtle, magnolia, maples. Look for: small bumps or crusty spots on bark or twigs that can be scraped off.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Insect
- Crape myrtle
- Magnolia
- Maples
- Tulip poplar
- Hemlock
- Pines
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
0 of 6 signs ticked. Ticks stay in this browser only.
Season
Young scales, called crawlers, move in spring and early summer and are the easiest stage to treat. Timing differs by species and region.
How it spreads
Crawlers move short distances on wind, birds, insects and people. Moving infested plants can carry scales to new areas.
Where it is found
Scale insects are a large group found on trees across the United States, with different species in different regions. Check your state official map; ranges change.
Official sources
What to do
- 1
Scrape a bump with a fingernail. A juicy or colored spot underneath means the scale may be alive.
- 2
Find out which scale it is. Armored and soft scales need different timing and treatment.
- 3
Ask an arborist about horticultural oil, which smothers many scales when it covers them well.
- 4
Time treatments to the crawler stage when possible. Sticky tape wrapped on twigs can help you see when crawlers appear.
- 5
Skip broad-spectrum sprays. They kill the helpful insects that eat scales.
Safety first: do not climb, do not cut near power lines and do not use a chainsaw on storm-loaded wood. Call the utility for downed lines and 911 if anyone is in danger.
Prevention
Keep trees watered and mulched, and avoid too much nitrogen fertilizer. Inspect new plants before buying. Prune out lightly infested twigs. Encourage natural enemies like lady beetles and tiny wasps.
When to call a pro
Call a pro when honeydew and sooty mold are heavy, when twigs are dying back, or when the tree is too tall to reach and spray. An arborist can name the scale and set the right timing.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: Crape myrtle, Magnolia, Maples, Tulip poplar, Hemlock, Pines, Many other trees and shrubs.
- Crape Myrtle
- Southern Magnolia
- Red Maple
- Silver Maple
- Japanese Maple
- Tulip Poplar
- Eastern Hemlock
- Eastern White Pine
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain scale insects to a customer
Be honest that sooty mold is mostly a cosmetic issue and that scales are often a stress-related problem, not just an insect problem. Explain that identification and timing decide whether treatment works. Offer a clear plan and say what you cannot promise.
Send this page to the customer after your visit so they can read the signs in plain words. See also selling plant health care and the job photo checklist.
Questions
Are scale insects really insects?
Yes. They are small insects that look like bumps. Many cover themselves with a shell or wax coating so they look like part of the bark.
What is the sticky stuff under my tree?
It is usually honeydew, a sugary waste from soft scales and some other insects. Black sooty mold often grows on it.
Does sooty mold harm the tree?
Mostly it makes leaves and surfaces look dirty and can reduce light on leaves a little. The bigger worry is the insect that is feeding on the tree.
Can scale kill a tree?
Heavy scale can weaken a tree and kill twigs or branches, especially if the tree is already stressed. Some species can cause serious decline.
When is the best time to treat?
Often during the crawler stage in spring and early summer, but it depends on the scale species. Dormant oil can work on some armored scales. Ask your extension office.
Do systemic products work on all scales?
Not all. Extension sources say soft scales are generally easier to reach with systemics than armored scales. An arborist can tell you which you have.
Can Lirevon diagnose scale insects on my tree?
No. Lirevon is a remote marketing team for tree service companies and does not do tree work. This page is general information, not a diagnosis. A certified arborist or your county extension office can confirm what is wrong with your tree.
How do I find a good local pro for this?
Search Google Maps for certified arborists or tree services near you, read their reviews and ask for proof of insurance. Get two or three written quotes. Our guide on how to hire a tree service lists the questions to ask.
Related tree problems
- Drought Stress (Other damage)
- Aphids (Insect)
- Girdling Roots (Other damage)
- Sooty mold (Disease)
- Construction Damage (Other damage)
- Frost cracks (Other damage)