Tree problems · Insect
Leafminers: signs and what to do
Leafminers is an insect pest, often seen on holly, birch, aspen. Look for: blotchy or winding tunnels (mines) inside leaves or needles.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Insect
- Holly
- Birch
- Aspen
- Elm
- Arborvitae
- Other trees, depending on the leafminer
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
0 of 5 signs ticked. Ticks stay in this browser only.
Season
Many leafminers lay eggs shortly after leaves expand in spring. The larvae then feed inside the leaf. Some species have one generation a year and others have more.
How it spreads
Adults fly to new leaves and lay eggs on or in them. Larvae feed inside the leaf, so they are hard to reach. Many drop to the ground to pupate, often in the soil or leaf litter.
Where it is found
Leafminers of many kinds live across the United States. Check your state official map and your county extension office for the species near you; ranges change.
Official sources
What to do
- 1
Look closely at the damaged leaves. Pull a mine apart and check for a larva inside.
- 2
Take photos of the leaf and the whole tree and note the species.
- 3
For a small tree, pick off and destroy leaves that still hold active larvae, as extension guidance advises.
- 4
Rake up fallen leaves so larvae cannot finish developing in the litter, if your extension office recommends it.
- 5
Ask your extension office before using any insecticide. Timing matters, and treatment usually works best when the adults are laying eggs in spring.
- 6
Water and care for the tree so it can recover.
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
Most leafminer damage has little effect on tree health. Keep trees watered and avoid stress, which can make problems worse. Choose species and sites suited to your area. Check new spring leaves to catch problems early.
When to call a pro
Call a certified arborist if a tree is losing many leaves for several years, if the tree is also stressed by other problems, or if it is too tall to check safely. Large trees need trained, insured crews and proper equipment.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: Holly, Birch, Aspen, Elm, Arborvitae, Other trees, depending on the leafminer.
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain leafminers to a customer
Say plainly that leafminer damage is usually cosmetic and that a spray is often not needed. Explain that timing is everything because larvae hide inside the leaf. Owners trust a company that does not sell a treatment the tree does not need.
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
What are leafminers?
They are small insects whose young feed between the top and bottom of a leaf. This leaves tunnels or blotches.
Will leafminers kill my tree?
Extension sources say most leafminer damage has little if any effect on plant health. Heavy damage on a stressed tree can be more serious. Ask your extension office about your tree.
Do I need to spray?
Usually not for small amounts of damage. If you do treat, timing matters, because treatment works best when adults lay eggs in spring. Ask your extension office first.
Can I just remove the leaves?
On small plants, picking and destroying leaves that still hold larvae can help. On big trees it is not practical.
Why do the leaves look blistered?
The larvae feed inside the leaf and leave a hollow, brown or pale patch. Pull one apart to see.
Will they come back next year?
Often yes, because the insects pupate in soil or litter and return. Check new leaves each spring.
Can Lirevon diagnose leafminers 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.
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