North Dakota State University Extension names the picture-winged fly, boxelder bugs and multicolored Asian lady beetles as the main fall home invaders. They overwinter in homes, favour older buildings and gather on warm south and west walls as temperatures cool. They are a nuisance rather than a danger, and screens and sealing are the main defence.
Key takeaways
- NDSU names the picture-winged fly, boxelder bugs and multicolored Asian lady beetles as the main fall home invaders.
- These insects overwinter in homes and favour older homes, according to NDSU Extension.
- They gather on the warm south and west walls as temperatures start to cool, and then look for winter shelter.
- They do not sting, do not destroy furniture or clothing and do not carry disease, according to the same extension guidance.
- Tight-fitting screens, especially on upstairs and attic windows and vents, and sealed gaps are the main defence.
Which insects are the main fall invaders in North Dakota homes?
North Dakota State University Extension names three: the picture-winged fly, which is often called the attic fly, boxelder bugs and multicolored Asian lady beetles. NDSU describes these three as insects that overwinter in homes.
The picture-winged fly is often called the attic fly. Multicolored Asian lady beetles are often mistaken for other lady beetles, so a careful identification matters before any plan is written.
All three gather in similar places on a building and respond to sealing in broadly similar ways. The point of naming them is not to make the work complicated. It is to help a homeowner recognise what is in the house and to ask the right questions about it.
Why do they gather on the warm south and west walls?
NDSU reports that these insects gather on warm surfaces, and the sunny south and west walls warm up in the afternoon. As temperatures start to cool, the insects slow and look for winter shelter, and the openings on those walls are where they find their way in.
Insects looking for shelter are drawn to surfaces that hold heat. A wall that catches the afternoon sun becomes a meeting point, and the insects that gather there look for a gap nearby. The south and west sides of a house are the usual places to see the activity.
The sunny walls are also where the siding joints, the window frames and the vents sit. A homeowner who walks those walls on a sunny afternoon will see the insects and the openings close together, which makes the check much easier.
Why do older homes have more of a problem?
NDSU Extension says these insects favour older homes. Older buildings tend to have worn screens, loose vent covers and more joints where insects can get through. A newer house can still have openings, so an inspection is the way to know which applies to yours.
Older houses have had longer to develop the small gaps that let insects in. A screen that has sagged, a vent cover that no longer closes and a window frame that has pulled away from the siding are all common over time. None of them is unusual, and each is a simple repair.
A newer house is not immune. Gaps left by building work, around pipes and cables, can be as useful to an insect as an old gap. The report from an inspection is the way to find the openings in the house in front of you.
Are these insects dangerous to people or to the house?
According to the same extension guidance, these insects do not sting, do not destroy furniture or clothing and do not carry disease. They are a nuisance rather than a danger, though they can leave a mess and are unwelcome in living space.
A nuisance can still be hard to live with. A room full of insects on the windows, or insects in the living space during the cooler months, is unpleasant, and many homeowners want them out. The concern is about comfort and mess, not about harm to the building or to the people in it.
That is a reason to keep the approach proportionate. A strong spray in the living space is not the answer, since it does not close the openings and can leave residue on surfaces. The sealing and screening work is the most useful response.
What are the most effective steps for a homeowner?
Use tight-fitting screens, especially on upstairs and attic windows and vents, and seal the gaps on the warm walls. Vacuum or remove the insects from the living space rather than swatting them, and keep the attic and the wall voids checked. These steps address the route rather than the insects alone.
Start with the screens and vents, since NDSU points to them most clearly. Replace any screen that does not fit its frame, and fit a fine mesh cover to any vent that lets insects through. A screen that is a few millimetres out of line is enough.
Seal the gaps around pipes, cables and window frames on the warm walls. Check the attic from the access point and the soffit from the ground. A technician can help find the openings, and the report lists each repair.
When is a visit from a technician worth it?
A visit is worth it when the openings are hard to find, when insects are coming in from several sides of the house or when the problem returns each autumn. The technician maps the openings, recommends the repairs and places any treatment where the inspection shows activity.
A technician's inspection is most useful for an older house with many openings, a house with insects from several directions or a house with a history of repeat problems. The report sets out the openings and the repairs in the order they should be done.
The visit can be booked by phone at any hour, and a same-day visit is offered when a technician is free. No same-day visit is guaranteed. The price is explained on site and approved before any work starts.
What should I do this autumn?
Walk the warm walls on a sunny afternoon, check the screens from inside, note the vents and the gaps, and fix the simple ones before the cold weather. Keep a list of the openings and check it again after the first cold snap.
Start at the south-west corner of the house, since those walls collect the most activity, and work round. Note the screens, vents, joints and penetrations as you go, and take photographs if the insects are hard to catch.
Make the simple repairs first, then book the work that needs a tradesperson. A second check after the first cold snap shows which openings have reopened or which new ones have appeared.
How do I check the attic without making things worse?
Use the access point, a torch and gloves, and keep to the joists. Do not disturb insulation more than needed, and do not sweep insects into the living space. Look for droppings, dead insects and the light from outside that shows a gap.
The attic is where insects that came in through a vent often collect. From the access point, look along the rafters and the vent openings, and note any spot where daylight comes through the roof sheathing or the gable. Mark the spots and leave the insulation as you found it.
If the attic is not safe to enter, do not enter it. Note what you can see from the access point and ask a technician to check the rest. A ladder and a helper are needed for any work near the vents from the outside.
How can I tell whether insects are getting in or just arriving?
Insects that are getting in tend to appear in the same places and the same numbers over several days, and they often gather near a particular gap. Insects that have arrived and stayed are more likely to be found in corners and around light. A short observation shows which is happening.
Watch the warm wall and the window frames on a sunny afternoon for a few days, and note where the insects settle. If they appear in a particular spot each day, look closely there for a gap. If they are found mainly inside, check the windows and the light fixtures near the activity.
Keep a record of what you see and where. The record helps a technician focus the visit on the openings that matter, and it shows whether the sealing work has reduced the activity over the next few weeks.
Frequently asked questions
What are the main fall invaders in North Dakota?
North Dakota State University Extension names the picture-winged fly, boxelder bugs and multicolored Asian lady beetles as the main fall home invaders.
Do fall invaders bite or sting?
According to NDSU Extension guidance, these insects do not sting, do not destroy furniture or clothing and do not carry disease. They are a nuisance rather than a danger.
Why do they come in during the cooler months?
As temperatures start to cool, these insects slow down and look for winter shelter. They gather on the warm south and west walls, and the openings there are where they find a way in.
Are older houses more affected?
NDSU Extension says these insects favour older homes. Older buildings tend to have more worn screens and gaps, but a newer house can have openings too, so an inspection is the way to know.
Is a fogger a good answer?
Usually not. A fogger does not close the openings and can scatter the insects into other rooms. Sealing and screening are the durable fix, with any treatment placed where the inspection finds activity.
Should I call before or after they are inside?
Before is better, because sealing works best before the insects have found the way in. If you have seen insects gathering on the warm walls, that is a good time to call or to check the openings yourself.
Do I need a technician for every fall?
Not necessarily. A house that was sealed and screened well may need only a yearly check. A technician is useful after a new problem appears, when the openings are hard to find, or when the same problem returns despite your own work.
Can a window screen be replaced without a technician?
Usually yes. A replacement screen is a small job for a homeowner who can measure the frame, buy the right mesh and fit it square. If the frame is damaged or the window is hard to reach, a technician or a repair person can make the fix instead.
Sources
This guide is general information for Burleigh County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.