Most people recognize common household pests like ants, spiders, and flies, but seasonal nuisance insects such as elm seed bugs and boxelder bugs can cause confusion. These two insects look somewhat similar, often appear around the same time of year in Idaho, and both invade homes in large numbers. Understanding the differences can help you identify what you are dealing with and determine the right prevention and control steps.
Differences Between Elm Seed Bugs and Boxelder Bugs
Although they behave similarly, elm seed bugs and boxelder bugs have several key differences.
1. Appearance
Elm Seed Bugs
- About one quarter inch long
- Dark brown with a distinct reddish pattern on the wings
- Red abdomen visible when they fly or are crushed
- Triangular shield shape with lighter banding
Boxelder Bugs
- About one half inch long
- Dark gray or black with bright red or orange lines along the wings
- Body shape is more elongated and flattened
2. Host Trees and Habitat
Elm Seed Bugs
- Strongly associated with elm trees
- Become heavy around neighborhoods with mature elms
- Often enter homes during hot mid summer conditions
Boxelder Bugs
- Strongly associated with boxelder, maple, and ash trees
- Common around homes with south or west facing walls where they warm themselves
3. Diet
Elm Seed Bugs
- Feed primarily on elm seeds
- Do not damage buildings or household items
Boxelder Bugs
- Feed on seeds and leaves of host trees
- Do not cause structural damage
4. Behavior
Both insects are primarily nuisance pests, but:
- Elm seed bugs release a noticeable odor when crushed
- Boxelder bugs tend to gather in large clusters on sunny exterior walls
Neither insect bites, spreads disease, or damages homes.
What Elm Seed Bugs and Boxelder Bugs Have in Common
- They enter homes through small cracks, gaps, and screens.
- Both are related to the broad stink bug family and can produce an unpleasant odor when crushed.
- They gather in large numbers on warm exterior walls.
- Fecal spots may stain siding, curtains, and walls.
- Neither is harmful to people or pets, but both are extremely annoying.
These insects become most active during hot weather and again in late summer as they seek cooler sheltered places, including homes.
How to Get Rid of Elm Seed Bugs and Boxelder Bugs
If you have these insects inside your home, there are several effective steps to reduce activity.
1. Seal Entry Points
Inspect and seal:
- Gaps around doors and windows
- Foundation cracks
- Gaps in siding
- Openings around utility lines
- Damaged window screens
Even very small openings can allow hundreds of insects to enter.
2. Reduce Indoor Activity by Vacuuming
Use a vacuum to collect insects and dispose of the bag immediately. Avoid crushing them on surfaces because they may leave stains or odors.
3. Exterior Barrier Treatment
A properly applied exterior perimeter treatment performed by a licensed professional is one of the most effective ways to reduce seasonal invasions. Products available to homeowners typically do not provide lasting control.
4. Ongoing Prevention
Because these insects return every year, many Treasure Valley homeowners choose seasonal maintenance services to prevent large populations from gathering on exterior walls and entering the home.
If you are dealing with frequent or heavy activity, a professional pest control service can identify the insect, assess entry points, and create a long term treatment plan.