Stink Bug Exclusion in Gaithersburg, MD

When do stink bugs come into houses in Maryland?

The Maryland Department of Agriculture puts the flights to overwintering sites from the middle of September through October, and another state document extends that to October through November. The practical conclusion is to have sealing done in late summer, before the insects are on the walls.

They reappear inside on warm days through the winter and into spring, which catches people out. Those are not new arrivals; they are the ones that got in during autumn and have been overwintering in a void.

That is why exclusion beats treatment here. Once they are inside a wall cavity, the options narrow to vacuuming them as they emerge. Our guide to stink bugs and fall invaders in Maryland sets out the seasonal pattern.

Do stink bugs bite or damage the house?

No. The University of Maryland Extension notes they do not bite, and they do not breed indoors or damage the structure. The complaint is numbers and smell: they gather in large groups, turn up indoors on warm days, and release an odour when squashed or disturbed.

That shapes a sensible response. There is no urgency about health or structural damage, so the work can be planned for the right time of year rather than rushed, and that right time is before the autumn flights.

For the ones indoors, the Extension says to vacuum them or release them outside. A vacuum kept for the purpose, or a bag emptied outdoors straight away, avoids the smell lingering in the machine.

What exactly gets sealed?

The gaps the insects actually use: window and door surrounds, weather-stripping, trim and siding joints, soffit and fascia junctions, utility and cable penetrations, vent screens, attic hatches, recessed light fittings and the gap around any window air conditioning unit, which the Extension advises removing.

Prioritise the elevations that take the afternoon sun, because that is where they gather before they go in. On many houses one wall supplies most of the problem, and sealing that wall properly is worth more than a light pass over all four.

Inside, the routes that matter are the ones between a wall void or attic and the room: a recessed downlight, an extract fan housing, an attic hatch, the gap behind a window architrave. Those are usually simple to close and they are what stops the midwinter appearances.

• Caulk cracks and joints at window and door surrounds and trim
• Fit or replace weather-stripping on doors, windows and the garage service door
• Remove window air conditioning units before autumn, as the Extension advises
• Repair torn vent, soffit and attic screens
• Seal utility, cable and pipe penetrations
• Close interior routes at recessed fittings, extract fans and the attic hatch

Will spraying the outside of the house keep them out?

Not on its own. An exterior treatment at the gathering surfaces ahead of the flights can reduce numbers, but a building with open gaps keeps admitting insects, and the state and university advice for this pest is mechanical: caulk, weather-strip and remove window air conditioners.

That is an unusual thing for a pest page to say, and it is the honest position. The sealing work keeps performing for years; a treatment is a season at best.

If you want both, do the sealing first and treat second. Done the other way round, you pay for a treatment and then open the wall up again with the caulking gun.

What moves the price of exclusion work?

The size and height of the building, how many openings and penetrations there are, the condition of the existing caulk and weather-stripping, how much of the work is at height, whether attic and interior sealing are included, and whether any exterior treatment is added. The price is confirmed on site.

It is closer to a maintenance job than a treatment job, and it should be quoted that way: a list of locations and what is being done at each. That also gives you something to check the following year.

No dollar figures appear anywhere on this site, because no sourced local figure exists. Ask what is included at height, since fascia, soffit and upper window work is where quotes differ most.