Flatheaded Appletree Borer
A flat-headed grub that mines under the bark of newly planted and stressed trees, almost always on the sunny side of the trunk. The bark over its tunnel dies and sinks in.
Pest checklist
Four things to look for. If most of them match what you are holding, you are in the right place.
What gets rid of them
Gentlest option first. For most backyard cases the first one is enough, so try these in order and stop as soon as it works. If you do spray something, the product label tells you how — please read the notice further down.
1Wrap or shade the trunk
Use a light-colored trunk wrap or a white spiral guard from planting through the first couple of growing seasons so the bark does not bake and crack.
tree trunk wrap white guardTry this first2Water the new tree
Drought stress is what draws this beetle in. A slow deep soak in dry spells does more than any spray.
tree watering bag slow release3Stop nicking the trunk
Keep string trimmers away and mulch a wide ring instead of mowing right up to the bark.
4Cut out a single grub
On a young tree worth saving, slit the bark along the tunnel with a knife, lift the grub out, and leave the wound open to callus over. Do not paint it.
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Which plants get flatheaded appletree borer
Every plant we cover that gets flatheaded appletree borer, grouped by type — tap any one to open its page. A note beside a plant came from that plant’s own entry, because the same pest can be a minor nuisance on one plant and a serious problem on another. Plenty of plants we do not cover get it too.
Plant families hit hardest
Related plants often share the same problems, so if one plant in a family has it, check the others. The largest group here is Rosaceae, with 3 of the 9 affected plants.
- Rosaceae3 plants
When to treat
Prevention only. Once the grub is under the bark of a small trunk the tree is usually lost, so protect the trunk from the day you plant, especially through the first two summers.
Timing only — the label is the law
This page tells you when to watch for flatheaded appletree borer and when treating is worth considering. It is not a recommendation to apply any particular product. Read and follow the product label before you spray — under federal law the label is the legal instruction, and using a pesticide against it is illegal.
- Check the pre-harvest interval. Every product that’s cleared for an edible crop sets a minimum number of days between spraying and picking. Find it on the label before you spray anything you intend to eat.
- Check the re-entry interval before you or anyone else works in the treated area again, and use the protective equipment the label names.
- Confirm the product is registered for your crop in your state. This page groups many different crops together, and a product legal on one of them is not legal on all of them — state registrations differ too. Your state pesticide agency or local extension office can confirm both.
- Rates and mixing instructions come from the label, never from us. We don’t publish them because they differ by product and formulation.
Other problems on the same plants
If a plant gets flatheaded appletree borer, these are the problems it most often gets as well, so they are worth checking for while you are out there. They tend to appear together; one does not cause another.