· by Michael Blair, Nashville's Pest Control
Every autumn in Middle Tennessee brings the same sequence: brown marmorated stink bugs on the south wall, ladybugs at the upstairs windows, camel crickets in the crawl space and spiders in the corners. These are overwintering pests rather than an infestation, and treating them as an infestation is why so much money gets spent for so little effect.
What they are actually doing
Overwintering insects are looking for a protected space to spend the cold months inactive. They are drawn to warm sunlit walls in autumn, typically the south and west faces, and they work their way in through the gaps that any house has around trim, siding, vents and the roof line.
Once inside they head for wall voids, attics and crawl spaces rather than living space. The ones you see in a bedroom in January are the ones that got confused by the warmth and came the wrong way. They are not breeding indoors and they are not feeding on anything in the house.
Why indoor spraying disappoints
Spraying the inside of the house kills the individuals you can see and does nothing about the far larger number sitting in the wall cavities. Two days later there are more, because the supply is coming from outside and from voids the spray never reached.
It also creates a secondary problem. A quantity of dead insects inside a wall attracts carpet beetles and other scavengers, which then move into the house looking for more. The pest treatment produces the next pest.
The treatment that works, and its window
Exclusion first: sealing the ways in. Caulk around window and door trim, screen the gable and soffit vents, fit door sweeps, seal where utility lines penetrate the wall, and repair the torn crawl space screening. This is the durable part and it is worth doing whether or not anyone sprays.
A perimeter treatment on the exterior walls has real effect, but only if it goes on before they move in, which in Middle Tennessee means late summer to early autumn. Applied in November it is treating a wall the insects are already behind, and the timing is the whole difference between it working and not.
- Seal gaps at trim, vents, utility penetrations and the roof line
- Fit door sweeps and repair window screens
- Exterior perimeter treatment in late summer, not in autumn
- Vacuum rather than spray or squash the ones indoors
- Reduce leaf litter and mulch piled against the foundation
Handling the ones already inside
Vacuum them. It is the least unpleasant method and it avoids the smell that gives stink bugs their name, which is released when they are crushed or threatened. Empty the vacuum outside afterwards, since the odor will otherwise stay with the machine.
Camel crickets are the Middle Tennessee specialty and they signal something about the crawl space rather than the house. They want dark and damp, so a crawl space with a good ground vapor barrier and controlled humidity stops being attractive to them, which does more than any spray.