bed bugs

Well I'd thing that both would WANT to get rid of them!  If it can proven that the tenant is the cause of the infestation (i.e the tenant brought the mattress/bed into the unit), it is the tenant's financial responsibility to remedy the infestation.  If I were the landlord, I'd want to have come amount of control over the process so that I could be assured that the problem was fixed once and for all.  The cost can be charged by the Landlord to the tenant.  As always, check the terms of the lease and follow those terms explicitly.