I went and bought Ortho Home defense and sprayed in both units especially in the small areas.

Birs spray seeds and thus attract mice and some bugs.

(I have had tenants turn the AC off when they move out or the heat in winter)- We require they have someone check on the property if they leave it for more than 5 days (This is to make sure there are no water leaks or HVAC issues that lead to problems while they are gone)- No businesses can be run from the property (to prevent day care, laundry services, gambling, drugs or who knows what)- We specify yard care includes week spraying and cleaning up sticks less than 1" in diameter (otherwise tenants think yard care is mowing only)- We state that tenants utilities can be used for routine maintenance or repairs (I once had a tenant complain the roofers were using his power for their compressors)- We have a whole section on mold stating that mold is naturally occurring and results from excess moisture.

Tell him to feel free to treat the personal property if appropriate (example, roaches love cardboard so if there are cardboard boxes, spray the outside of them.  

I do annual spraying. 

A lot of people think they're going to love it here until they get here and realize visiting a resort (with 24/7 A/C and weekly pesticide spraying) isn't quite the same as really living here. 

So, they can actually be your eyes on the condition of the property.In your shoes, if you think they are causing the problem, I'd suggest you have a pest control that must enter the unit as well as spray outside - once a month.  

Ever smell the results of a Tom cat spraying everywherer?  

Right now I'm spraying the stairs and about 24" up on all the walls.  

You can't just spray some cheap ozone stuff and it goes away.