In severe infestations, especially when the tenant has been attempting self treatments, the bugs are widely scattered throughout the suite. The bugs are in the walls, light fixtures, hardwood floor cracks, behind door and window frames, and sometimes even behind the kitchen cabinets! Basically it is impossible for even the best exterminator to access the vast majority of these bugs. When we begin treating these suites with standard chemicals and glue boards it is common to get a huge rush of bugs (thousands) in the first month which then tapers off to a dribble of bugs a few months later. It is that later dribble of bugs that is the most problematic.
When we start with these projects it is always useful to go through the suite with standard chemical treatments to reduce the sheer number of bugs. The chemicals will also chase the bugs out of dressers and other furniture. This is helpful. But after the third chemical treatment it is common to see very few (if any) bugs on the items that were previously treated. The 4th treatment is ineffective as everything the exterminator could hit has already been hit – respraying bug free areas is not effective. The remainder of the bugs are slowly leaking out of walls, electronics, light fixtures, etc that the exterminator could not access.
In these cases I recommend foregoing the 4th and 5th chemical treatments and rely on the modified glue boards to mop up the remainder of the infestation. The chemical treatments are ineffective in wall cavities – why waste the effort? Of course one must have the ability to cooperate with the bed isolation and laundry protocols or the bugs will again restart the population explosion. If there is no cooperation then chemical treatments must continue.
Some exterminators attempt to address the inaccessible bugs by injecting aerosol pyrethrin directly into every crack and hole they can find in the hope of directly hitting them directly. The problem with this method, especially in multi family settings, is the bugs explode across the building. You then start finding bed bugs in the spider webs on the windows of other suites that previously had no bugs. Or the bugs pour out of the bathroom vents into other suites. Or the bugs migrate by the thousands down public corridors. That $15 can of aerosol can cause thousands of dollars damage to other suites. But I suppose the exterminator is right there to fix those suites as well – and send his own kids to college with the proceeds. As a landlord I would fire any exterminator that attempted that procedure. The modified glue board protocol is far cheaper and causes much less hardship to neighboring suites.