I'm a new landlord and new to MA. I rent the four rooms out to the tenants in my apartment in the beginning of 2011. In July, one of my tenant notified me on the existing of bed bugs. I spoke to a exterminator and understand that the bed bugs were brought into the house from others as there were no bed bugs in the house from the start. I agreed to have a exterminator come in to have these treated as this is part of the law that landlord has to deal with it even though landlord has nothing to do with the bed bugs (the house has no bed bugs from the beginning).
Anyway, is there any law to protect the landlord on this kind of issue? If on the Lease Agreement, landlord and tenant agreed the to no matter what kind of bugs in the house, landlord has no responsibility on paying for the treatment. Can this take effected if it's written on the Lease Agreement? For example, as the issue above, if the landlord and tenant agreed on landlord will not pay for the treatment on bed bugs on the Lease Agreement, then will this work when it comes to the MA law that landlord has to treat the bed bugs? If not, then what's the Lease Agreement for/mean if what's written on it does not take effected? I appreciate your time on writing your response/advise. Thank you!

Who exterminates bed bugs
I don't think so. Massachusetts law places the responsibility for exterminating all manner of bugs and vermin, including bed bugs, on the landlord. And you cannot avoid that responsibility by adding language to a lease. Even if you could, with a multi-unit building, you could never be sure who brought the bugs into the building.
However, you can require that all tenants have their furniture treated before moving into your building. I'm not sure of the logistics, but you should talk to a local exterminator about the process. I assume they can provide the tenant with evidence of treatment that you can inspect.
bed bugs
What you might do is have a bed bug sniffing dog come in and locate the source. If I were a landlord, I would make sure my facility is clear of bed bugs. Then going forward I would have the dog come in on a quarterly or three times anually basis to ensure that they don't come back. It is much easier and cheaper to treat low infestations and the dog will help ensure that. I would also require all new tennants to have their belongings pre inspected as a condition of their tennancy (at their exspense)or you don't allow them in. My partner and I have such a dog that has been trained to detect bed bugs. We are based in Worcester MA. for extensive information visit our website www,massbedbugbusters.com