Emerald ash borer has now been confirmed in every single Indiana county, and Michiana is no exception. Since its first detection in Michigan in 2002 and its spread into Indiana shortly after, this invasive beetle has killed hundreds of millions of ash trees across North America. If you have ash trees on your property in South Bend, Elkhart, Goshen, or anywhere in the surrounding area, this guide covers everything you need to know to make informed decisions before it is too late.

What Is Emerald Ash Borer?

Emerald ash borer, or EAB, is a small metallic green beetle native to Asia that was accidentally introduced to North America through wooden shipping materials. The adult beetle is only about half an inch long and causes no direct damage itself. The problem is what happens after it lays eggs.

Larvae hatch beneath the bark and feed on the phloem, the tissue that carries nutrients and water between the roots and the canopy. As larvae tunnel through this layer in S-shaped galleries, they cut off the tree’s ability to move water and nutrients. The tree slowly starves from the top down, and without intervention, death typically follows within 2 to 5 years of infestation.

100%
of Indiana counties now have confirmed EAB presence
8 billion
ash trees estimated in North America at risk
2 to 5 yrs
typical time from infestation to tree death

EAB attacks all native North American ash species including green ash, white ash, black ash, and blue ash. There are no ash species that are immune. Every ash tree in Indiana should be considered at risk.

How to Identify Emerald Ash Borer on Your Trees

EAB is difficult to detect in its early stages because the larvae work beneath the bark out of sight. By the time symptoms are visible from the ground, the infestation is often already well established. Here is what to look for:

D-Shaped Exit Holes

The most definitive sign of EAB is the distinctive D-shaped exit hole adult beetles leave when they emerge from the bark in late spring and early summer. These holes are about the diameter of a pencil tip, roughly 3 to 4 millimeters wide, and flat on one side making them distinctly D-shaped rather than round. They can appear anywhere on the trunk and major branches.

💡How to find exit holes: On a sunny day, run your fingers along the bark of the trunk and lower branches. The holes are small but the edges are distinct. A magnifying glass helps on rough-barked trees like mature white ash.

S-Shaped Galleries Under the Bark

If you peel back a section of bark on a suspected tree, EAB-infested trees show serpentine S-shaped tunnels packed with fine sawdust-like frass. These galleries are the feeding paths of the larvae and they wind back and forth across the grain of the wood in a distinctive pattern that no other common pest replicates exactly.

Crown Dieback Starting at the Top

As the infestation progresses and the tree loses its ability to move water and nutrients, the canopy begins dying from the top down. You will notice thinning foliage, dead branch tips, and entire upper branches going bare while the lower canopy still looks reasonable. This top-down dieback pattern is characteristic of EAB and differs from other diseases that typically cause more scattered dieback throughout the canopy.

Epicormic Sprouting

Heavily infested ash trees often produce dense clusters of sprouts along the lower trunk and at the base. This is the tree’s stress response, essentially a last attempt to push out new growth below the damaged area. It looks unusual because sprouts emerge directly from the bark of the trunk rather than from branches. If you see this on an ash, the tree is in serious decline.

Increased Woodpecker Activity

Woodpeckers feed on EAB larvae beneath the bark and are often the first indicator that something is wrong before visible symptoms appear. A sudden increase in woodpecker activity on an ash tree, particularly flaking bark or vertical strips being peeled away, is worth investigating closely.

⚠️Do not wait for all symptoms to appear: By the time you can see crown dieback clearly from the ground, the tree has often lost 30 to 50 percent of its canopy. At that point, treatment success rates drop significantly. Acting on early signs gives you far more options.

Can an Infested Ash Tree Be Saved?

Sometimes yes, but it depends entirely on how far the infestation has progressed. The general rule used by most arborists and extension services is the 30 percent threshold: if a tree has lost 30 percent or more of its canopy to EAB-related dieback, treatment is unlikely to be successful enough to justify the ongoing cost.

Trees that still have 70 percent or more of a full, healthy canopy can often be saved with systemic insecticide treatments. Trees below that threshold are generally best removed before they become a hazard.

Treatment Options for Ash Trees in Indiana

There are two main categories of EAB treatment available to Indiana homeowners:

Soil injection and basal bark treatments: Products containing imidacloprid or dinotefuran are applied to the soil around the base of the tree or directly to the lower bark. The tree takes up the insecticide through its root system and it moves into the tissue where larvae feed. These treatments are widely available and can be applied by homeowners on smaller trees, though professional application produces better results on large trees.

Trunk injection: Products containing emamectin benzoate are injected directly into the tree’s vascular system using specialized equipment. This method requires a licensed applicator but provides longer lasting protection, typically 2 to 3 years per treatment versus annual application for soil treatments. Trunk injection is generally considered the most effective option for high-value ash trees.

“A healthy ash tree treated before significant infestation has a strong chance of long-term survival. The same treatment applied after 40 percent canopy loss is largely money spent on a dying tree.”

The Economics of Treatment vs. Removal

Treatment is not free and it is not a one-time cost. Systemic treatments need to be reapplied every 1 to 3 years indefinitely as long as EAB pressure exists in the area, which in Michiana means essentially forever at this point. Before committing to treatment, consider:

  • The size and health of the tree relative to treatment cost over 10 years
  • The structural value the tree provides in terms of shade, privacy, and property value
  • The cost and disruption of removal now versus removal of a larger, more hazardous dead tree in 3 years
  • Whether the tree is close enough to your home that a failing dead tree creates liability

For a large, healthy, well-positioned ash tree that would cost $3,000 to remove, committing to $200 per year in treatment is often the right financial call. For a medium ash in a location where removal would cost $500, years of treatment may not make economic sense. A professional tree health assessment can help you run those numbers for your specific situation.

When Removal Is the Right Call

There is a point where removal is clearly the better decision, and waiting past that point makes the job more dangerous and more expensive. Consider tree removal when:

  • The tree has lost more than 30 percent of its canopy to dieback
  • D-shaped exit holes are extensive across the trunk and major limbs
  • The tree is leaning or showing root instability
  • Dead branches are already falling
  • The tree is within striking distance of your home, garage, or a frequently used area of your yard
  • Treatment costs over 10 years would exceed removal cost

Dead ash trees become significantly more hazardous as they decline. The wood dries and becomes brittle faster than most other species, and dead ash has a particular tendency to drop large branches suddenly. A tree that looks stable in June can be dropping major limbs by September. We see this every season in the Michiana area.

⚠️Dead ash trees are more dangerous than most dead trees: Ash wood loses structural integrity faster than oak or maple after death. If you have a dead or dying ash near your home or a frequently used area, do not put removal off until next season.

The EAB Situation Specifically in Michiana

St. Joseph County and Elkhart County have both dealt with significant EAB impact for years. The urban ash tree populations in South Bend and Elkhart in particular were hit hard in the first wave, and many street trees and residential trees have already been lost. What remains tends to be either trees that were treated proactively or trees in early to mid-stage decline that owners have not yet addressed.

If you have ash trees that have not been assessed in the past two years, the situation on your property may have changed significantly. EAB populations fluctuate seasonally and a tree that looked manageable two years ago may have crossed the treatment threshold since then.

We assess ash trees throughout our service area including South Bend, Elkhart, Goshen, Mishawaka, and all surrounding communities. Our assessment gives you a current picture of where your trees stand and an honest recommendation on whether treatment or removal makes more sense for each one.

What to Do Next

If you have ash trees on your property, here is a straightforward action plan:

  • Walk your trees this week and look for D-shaped exit holes, crown dieback, and woodpecker damage
  • If you see early signs, schedule a professional assessment now while treatment is still viable
  • If the tree is showing significant dieback or has been declining for more than a season, get a removal quote
  • If your ash trees look healthy, consider proactive treatment before EAB establishes

Michiana Tree Pros provides free tree health assessments with every removal quote. If you are not sure whether your ash trees need treatment or removal, call us at (574) 213-6355 and we will take a look at no charge. We serve South Bend, Mishawaka, Elkhart, Goshen, Granger, Niles MI, and all surrounding Michiana communities.