If it'd the buildings by Target side then you're fighting an uphill battle. Those older buildings have had the issue for years, possibly even more than a decade. It's infamous amongst local pest companies. The problem will never be solved for 2 reasons: the residents in the building are always changing and don't fully care or understand about keeping clean and the management doesn't want to pay the high cost to eradicate it. It would be somewhere in the $100K area to treat every unit and take an excruciating coordination effort by everyone involved. All they do is band aid treatments to keep people shut temporarily