We have had a lot of callouts in the last 2 weeks during lockdown with buildings empty, the main issue has been spiders and flies inside the smoke detector base and chamber

We spray the base of the device with insect and fly spray manufactured for the electronic industry, we also use cleaner dust spray to clean out dust and cobwebs.

(Hoovering a device while in place at a reachable height can minimise a lot of nuisance callouts for the property owner.)

Flies inside a smoke detector