Boxelder Bugs in Utah: Why They’re a Problem and How to Keep Them Away From Your Trees

If you live in Salt Lake City or anywhere along the Wasatch Front, you’ve probably seen these black-and-red bugs crowding on your trees, siding, or sunny walls in the fall. These are boxelder bugs, and while they might not look threatening at first, they’re part of a bigger story about tree health, seasonal pest pressure, and how small insects can cause long-term issues.

At Utah Tree Care, our focus isn’t pest control for your house. It’s the health of your trees and shrubs, and pests like boxelder bugs can be a symptom of an unbalanced landscape — especially if they keep coming back year after year.

Let’s break down what they are, what they mean for your trees, and how to prevent them the right way.

What Are Boxelder Bugs, Really?

Boxelder bugs are flat, black insects about a half-inch long with reddish-orange outlines along their backs and wings. They’re not dangerous, but they show up in huge numbers — especially in neighborhoods with lots of boxelder, ash, or maple trees.

These bugs feed on tree seeds, leaves, and young twigs, and they’re especially active in late summer and fall. They aren’t known to destroy trees, but if they’re feeding heavily on your young or stressed trees, they can weaken them over time.

Why Tree Owners Should Pay Attention

Seeing a few boxelder bugs isn’t cause for panic. But if they keep coming back in large groups each year, your trees may be dealing with bigger issues like:

• Chlorosis (yellowing leaves from poor iron uptake)

• Nutrient deficiencies in the soil

• Root stress from drought or compaction

• Lack of pest prevention

Stressed trees don’t just attract boxelder bugs—they also become targets for more destructive pests, like the Ash Borer.

What We Check During a Tree & Landscape Evaluation

Boxelder bugs don’t need to be sprayed away—they need to be prevented through better tree care. That starts with a detailed Tree and Landscape Evaluation, where we assess:

• Leaf color, branch health, and canopy density

• Chlorosis or signs of nutrient lockout

• Early pest signs (like borers or scale)

• Soil drainage, compaction, and root health

• How your site handles sun, water, and wind exposure

This helps us create a custom plan that improves your tree’s strength from the roots up—not just a temporary fix.

How Tree & Shrub Care Prevents Pest Issues Naturally

Healthy, well-fed trees are naturally more pest-resistant. Our Tree & Shrub Care program focuses on long-term health, not surface treatments.

Here’s how we help:

• Deep root feeding to restore essential nutrients

• Seasonal fertilization for balanced growth

• Targeted pest protection (only when needed)

• Ongoing health tracking to catch early stress signs

The result? Trees that look better, grow stronger, and hold up to seasonal challenges—including pest invasions.

Why HOAs and Commercial Properties Should Care

Managing a property like an HOA, school, or business park? Boxelder bugs aren’t just annoying—they stain walls, clog vents, and can hurt your curb appeal.

Worse, their presence might be warning you of bigger health issues across your landscape.

Our Commercial Tree Care team helps large properties:

• Keep tree health consistent site-wide

• Strengthen weak or declining trees

• Reduce long-term pest and disease risks

Signs Your Trees May Be Struggling

Watch for these red flags:

• Trees covered in black-and-red bugs every fall

• Early leaf drop or thinning canopy

• Yellow or pale foliage (chlorosis)

• Constant replanting or storm damage cleanup

These signs may point to deeper problems like nutrient deficiencies or early Ash Borer activity. The sooner you act, the more damage you can prevent.

Long-Term Impact of Recurring Boxelder Bugs

One season of bugs isn’t a crisis—but years of infestation combined with stress can lead to:

• Weak leaf production and reduced growth

• Increased drought sensitivity

• Greater risk of scale and borer infestations

• Long-term decline and higher replacement costs

Prevention is always more affordable than restoration.

Fertilizer Isn’t Always the Fix

A lot of people think,

“My tree looks off, I’ll just toss some fertilizer on it.”

Unfortunately, this can backfire. Too much nitrogen can weaken your tree, leading to soft growth that actually attracts more bugs.

Our approach with Tree & Shrub Care is tailored:

• Nutrition matched to tree species and age

• Timing aligned with seasonal cycles

• Includes organic matter, micronutrients, and soil conditioning

This boosts long-term resilience instead of just speeding up growth.

What About the Emerald Ash Borer?

If you’re seeing boxelder bugs, you might wonder if Ash Borer  is next. These beetles drill into ash trees, destroying them from the inside out—and Utah is seeing more cases every year.

Boxelder bugs often appear on the same weakened trees that later attract EAB. Our Emerald Ash Borer Utah service helps you:

• Detect early signs of borer infestation

• Protect at-risk ash trees

• Avoid expensive removals later on

When Should You Act?

The best time to care for your trees is before pests show up:

• Spring–Early Summer: Best for soil testing, chlorosis correction, and root care

• Mid–Late Summer: Ideal for nutrient treatments and pest prevention

• Fall: Time to prepare trees for winter and protect young plantings

Not sure where your trees stand? Our Tree and Landscape Evaluation will tell you exactly what your next step should be.

The Real Issue Isn’t the Bugs — It’s the Tree

Boxelder bugs aren’t deadly. But their presence is often a sign your tree is missing something critical—nutrition, water balance, or pest protection.

The good news? With the right support, your trees can bounce back stronger than ever.

Let’s Build Healthier Trees — Not Just Fight Bugs

At Utah Tree Care, we believe in prevention, not panic. We focus on long-term plant health, not band-aid solutions.

If your trees are struggling or showing signs of decline, now’s the time to act. We’ll help you restore balance, improve resilience, and avoid costly problems down the road.

📍 Visit: utahtreecare.com
📞 Call: (801)-870-0164
📧 Email: [email protected]

For in-depth, science-based info on boxelder bugs, visit the USU Extension Boxelder Bug Guide.