Can spiders set off a burglar alarm?
Yes, spiders are probably the number 1 cause of false alarms
Has your alarm triggered for no apparent reason? It may be you've been the victim of an 8 legged intruder - a giant spider.
Actually, in reality, they don't have to be huge to do this; all it takes is a spider to crawl directly over a sensor to fool it into thinking there's some kind of intruder. When you consider that a burglar alarm sensor's job is to detect movement at a distance of several feet, something moving over its direct surface is going to trigger it just the same.
So keep an eye out for cobwebs around your sensors and clear them straight away.
Apparently spiders don't like the scent of peppermint spray. Spray it around your home, especially up behind the sensors where spiders like to hide, and it will encourage any spiders to relocate. Tea tree and eucalyptus oil will achieve similar effects.
if your alarm does go off, your panel should tell you which zone has triggered it. Check for signs of webs on these sensors.