I think if your a carpet and upholstery cleaner, there wont be much demand.
Perhaps if you are a pest controller, then there probably would be.
As far as rodents go, I think the local councils handles these and there's also a plethora of would be assassins at the local air rifle club, dressed in combos with the latest night sight technology who would gladly take the little blighters out for free.
If my memory serves me right, Ive probably had 4 inquiries in ten years for fleas or carpet moth.
If you want a lucrative add on to your business that will generate £1000s of extra income a year, your probably better going for..