I talked to a professional painter friend. he had me spray a clorox /water  mix on all the walls about knee high down. and spray door frames heavy. 

If that happens is it up to me to go over there with my can of wasp spray and deal with it, or do you all let the tenants handle this? 

We are now planning a sitting garden, with a nice bench and flowers.During December we will give a small food gift, such as a jar of jam, box of candy, homemade bread, or hot cocoa.  

No dont want to do that just wondering if it might jar them into trying to pay or maybe even get in contact to make arrangements.

It also saves labor on sanding when you are installing new drywall and can be sprayed over concrete.  

@Matt GoodI used crossfire herbicide mixed with diesel,I cut them off and sprayed the stubs.The birds eat the berries and so it's an ongoing problem if nearby properties have green briars.Goats do a great job of clearing/cleaning up a place it seems they eat everything .    

I've found that spraying some WD40 on the rope and on the window tracks sometimes helps. 

hence why its vital to have a record/receipt of any rental property having been treated (ie, sprayed or 'heat' treated) in between each tenant.absent proof of  a preventative treatment before tenant moved in, its up in the air if they are blaming landlord for an allegedly pre-existing condition.i'd give them the option to vacate if they can't take care of the pest problem as its a single family detached.

We patch all holes when we can and have terminix spray the unit each time but these are just REACTIVE measures. 

Builder also notes that he had swapped the shower head for a junky version that sprays everywhere but is aimed at the back wall.