Summer is when your shade trees should be thriving; not slowly dying from the inside out.
Unfortunately, July and August are peak months for tree-boring insects in Michigan. These destructive pests tunnel beneath the bark, cutting off the tree's ability to move water and nutrients. By the time leaves begin turning yellow or branches start dying, the damage is often well underway.
The good news? Catching infestations early can often save the tree.
This guide explains how to identify tree-boring insects, recognize the warning signs, and know when professional treatment is needed.
Tree-boring insects are wood-boring beetles and larvae that tunnel beneath a tree's bark, damaging the tissue responsible for transporting water and nutrients.
Common Michigan tree borers include:
Most attacks occur on trees already stressed by:
Healthy trees are much more resistant to insect attacks.
Michigan's warm summer temperatures speed up insect development.
During July and August:
Because the insects spend most of their lives hidden inside the tree, homeowners rarely notice a problem until visible symptoms appear.
Several common landscape trees are especially vulnerable.
Ash trees remain at risk from the Emerald Ash Borer, even years after the initial outbreak. Untreated trees typically die within a few years of infestation.
Bronze Birch Borers commonly attack stressed birch trees during hot summers.
Oak species weakened by drought may attract Two-Lined Chestnut Borers.
Stressed maple trees can become susceptible to several bark beetle species.
Apple and crabapple trees may experience attacks from Flatheaded Apple Tree Borers.
Many homeowners first notice changes in the canopy rather than the trunk.
Watch for these warning signs:
Sections of the canopy begin looking sparse compared to previous years.
Individual limbs die unexpectedly during summer.
Small holes in the bark are one of the clearest indicators of Emerald Ash Borer activity.
Vertical cracks may reveal insect tunnels underneath.
Woodpeckers often remove bark while feeding on larvae hidden beneath.
If your tree suddenly attracts many woodpeckers, investigate further.
Fine sawdust or wood shavings can indicate insect activity.
Sections of bark begin peeling away.
New shoots emerge from the trunk as the tree struggles to survive.
Leaves begin changing color weeks before surrounding trees.
The tree appears healthy one season but rapidly deteriorates the next.
Trees transport water and nutrients through a thin layer just beneath the bark called the cambium.
Boring larvae feed directly on this layer.
As tunnels multiply, they eventually "girdle" the tree, preventing water from reaching the canopy.
Without treatment, many infestations become fatal.
Sometimes, but success depends on timing.
Surface sprays rarely reach insects already inside the tree.
Professional arborists often use:
Early treatment offers the highest chance of saving valuable trees.
Prevention is far easier - and less expensive - than removing a mature tree.
Michigan homeowners should:
Healthy trees naturally defend themselves by producing protective sap that discourages many insects.
Contact a certified tree professional if you notice:
Waiting until next spring often allows the infestation to spread.
Emerald Ash Borer, Bronze Birch Borer, Two-Lined Chestnut Borer, Flatheaded Apple Tree Borer, and several bark beetle species are among Michigan's most common tree borers.
Yes. Trees caught early can often recover with professional treatment and improved overall health. Severe infestations may require removal.
Adult activity typically peaks during late spring through mid-summer, while homeowners often notice damage in July and August.
Yes. Many boring insects spread from weakened trees to nearby susceptible hosts if infestations are left untreated.
Common signs include D-shaped exit holes, thinning leaves, bark splitting, heavy woodpecker activity, and shoots growing from the trunk.
Absolutely. Drought stress weakens a tree's natural defenses, making it much easier for boring insects to establish infestations.
Tree-boring insects often remain hidden until significant damage has already occurred. Regular inspections and timely treatment can make the difference between preserving a mature tree and facing a costly removal.
At Safari Tree, our certified arborists help Michigan homeowners identify early signs of insect activity, improve tree health, and recommend treatments that protect valuable landscape trees throughout the growing season.
If you've noticed thinning leaves, dead branches, bark damage, or increased woodpecker activity, schedule a professional tree inspection before the infestation worsens.
Early action is the best investment you can make in the long-term health and beauty of your trees. To protect your trees today, give Safari Tree a call at 888-956-1953.