Tenant/Landord Rights in Missouri

[Jamie Carter]

Hello! I have a duplex, one side I'm renting in, one side has renters. They have lived there about 2.5 years. Never had an issue with rent. However, during the summer, their bathroom sink started leaking due to a faulty faucet and didn't tell me for 1 month. When they told me, I pay for a plumber to take care of the issue and believe it is solved. Then approximately 2-3 weeks after that is fixed, they tell me there have been an infestation of bugs (no see-ums & supposedly "buffalo gnats") that have been biting them inside due to the leaky faucet because they supposedly started when the leaky faucet problems started. It's been a wet summer so I don't doubt the amount of bugs outside, but they start claiming these bugs are coming from the sewer. I pay Orkin $250 to take care of the issue and they claim they are still getting bit and they are still in the house. They decided that the house was deemed uninhabitable the SAME DAY that they tell me there are bugs in the house.

First, they asked for me to pay for a hotel room for them since they conveniently had nowhere to go. I respectfully declined due to that being a renter's insurance benefit. They moved in with their parents for about a month. They pay the rent twice a month on the first and 15th. They didn't pay the 1st of August, but paid the 15th of August. They then tell me that despite the 3 times that Orkin has been out there, that there are still biting bugs, but it has "gotten better." They failed to pay the 1st and 15th of September and informed me they put a contract on a house and planned on moving out at the end of October. 

I was thinking of withholding their security deposit due to unpaid rent. Should I pursue further action or no action at all? The rent is $655 a month, and their security deposit is $400. Thoughts from my fellow investors?