Install fine mesh screens behind air vents. Lets air flow but blocks spiders better than any gadget I’ve tried.
Bought a ‘spider-proof’ ultrasonic device that came with free sticky traps. Guess which part actually caught spiders? Hint: not the sound waves!
@MousePatrol Diatomaceous earth works great but be warned - it’s messy to clean up and can irritate lungs if you’re not careful during application.
Spiders’ vibration detection is so sensitive they can ‘hear’ your footsteps through walls. No wonder ultrasonic noise does nothing!