If the landlord specifically instructed the tenants not to move or touch the metal barrel, then tenants would be responsible for the damage, too (Landlord should remedy the situation ASAP and bill tenant back).

As colleges and universities move past their initial responses to the COVID-19 pandemic, including transitions to remote instruction and operations, higher education leaders are working diligently to plan for the future.

The EPA gives some really good information on dealing with bed bugs, identifying them, what to look for in a pest control professional, and what you can do going forward to prevent the problem (or in this case what you can instruct your tenants to do).https://www.epa.gov/bedbugsGood luck!!!

Tenant shall prepare the Dwelling Unit for the application of insecticides or pesticides in accordance with any written instructions of Landlord, and if insects or pests are found to be present, follow any written instructions provided by Landlord to eliminate the insects or pests following  the application of insecticides or pesticides.

And if you want to deduct anything from their security deposit, you have to first give them written notice of their right to an initial inspection that gives them detailed instructions on how to get their full deposit back, with the legal language in that written notice, about their rights.In CA, all fees, no matter what you call them, are considered part of the security deposit and fall under those laws.So, if you've been getting away with this in CA, you've been getting away with breaking the law.

@Mark Douglas, as @Kyle J.advises, give the tenant move-out instructions.

My lawyer instructed me to just post the warning notice

The info sheet has the number of bedrooms and baths, key features/selling points of the house, rent amount, security deposit amount, rental requirements, instructions for how to turn in a completed application and the amount of the screening fee, and my contact info. 

my experience with this in Oregon... is that when they file bankruptcy you will get a letter from the bank ruptcy trustee instructing you to return the last 12 months of garnishments ..

I clearly need to manage the PM better as well.I will respond that the tenant needs to show proof of pests and will instruct her on proper use of dishwasher (don't overload the machine, remove food particles).