A Silent Threat to Your Trees
Some trees start to go quiet in ways that don’t call attention to themselves. An ash tree might leaf out a little late, or drop a few more than usual by midsummer. You chalk it up to heat stress or root shock; nothing looks alarming from a distance. But up close, you notice fine cracks running down the bark, maybe a patch of woodpecker activity higher than normal. The outer signs always lag what’s happening inside.
Emerald ash borer doesn’t invade quickly, but it does infest without warning.
The Problem Starts Under the Bark
This beetle isn’t large; it’s a narrow, metallic-green insect only about half an inch long. Its impact shows up in the hundreds of millions of ash trees it’s killed since arriving in North America. The damage doesn’t come from the adults flying between trees. It’s the larvae, which bore into the cambium layer and feed on the tissue that carries water and nutrients.
As they carve through this network, the tree can’t heal or compensate. Water doesn’t reach the canopy, and new growth falters. Once a tree shows dieback in the top third of its canopy, it’s usually beyond saving.
How Infestations Spread
You won’t always know how it got there. Adult beetles can travel a few miles on their own, but most outbreaks are tied to firewood or timber being moved across regions. Even one log with hidden larvae can introduce the insect into a new area. That’s why local ordinances often restrict firewood movement, even when the tree looks clean.
In neighborhoods with mature ash plantings, one infected tree often leads to dozens more within a season or two. The beetles don’t stay isolated. If there’s food, they find it.
Signs to Watch Before It’s Obvious
If you have ash trees on your property, look closely at the bark. The earliest sign might be D-shaped exit holes, each about the size of a pencil tip. You might also notice vertical splits forming as the tree reacts to feeding damage beneath the surface.
Other red flags include excessive sprouting at the base of the tree, bark flecking from woodpeckers searching for larvae, and sections of thinning or yellowing leaves well before fall.
A tree can be infected for a year or more before showing these symptoms. By the time you see them, infestation is already underway.
When Prevention Is Still an Option
Treatment works best on trees that are still healthy. Once there’s more than 30–40% canopy loss, the odds drop significantly. For trees worth preserving—due to size, shade, location, or age—preventive care makes a real difference.
Most chemical treatments involve injecting systemic insecticides into the base of the tree. These get pulled into the tissue the beetles feed on, killing the larvae and disrupting their life cycle. This needs to be done on a schedule, typically every two to three years, depending on the product used.
Timing matters. Spring and early summer applications tend to be most effective, as that’s when larvae are active and adults begin laying eggs.
Why Full Removal Is Sometimes Necessary
Not every tree can or should be saved. If the bark is sloughing off in plates or more than half the crown is bare, it’s usually too late to treat. Dead or declining ash trees become brittle fast. Limbs break without warning, and entire trunks can fall during storms or heavy winds.
In urban or suburban areas, removal becomes a safety issue. Once the tree dies, it can’t hold itself upright for long. Acting early means avoiding costly damage or emergency removals later.
If one tree comes down, it’s worth having nearby trees inspected during the same visit. An arborist can help you decide which ones can be preserved and which should be taken out before the risk builds.
The Bigger Picture: Long-Term Approach
Emerald ash borer isn’t a pest you manage on one tree alone. Even if your property is clear now, the surrounding areas may not be. Healthy trees will need to be monitored. Preventive treatments have to be repeated. And replanting decisions should focus on species diversity to avoid future waves of loss.
Ash trees once made up a significant percentage of the urban and rural canopy in many parts of the country. That’s no longer the case in infested zones. But if you act early and know what to look for, you can give the ones still standing a better shot at holding on.
Tree Services of Omaha – Tree Removal Services
Tree Services of Omaha, Nebraska is a full-service tree care provider that offers a wide range of arborist services including but not limited to: Tree Removal Services, Tree Trimming, Tree Pruning, Tree and shrubs Shaping, Stump Removal, Stump Grinding, Emerald Ash Borer Treatment, Arborist Consultations, Systemic Tree Injection (Tree Healthcare).
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