How can I tell if the pest control company did a good job of pretreating my house?
Other than drilling through the concrete slab, pulling a soil sample and having the sample analyzed for termiticide residues, there is no good easy way to tell if your house was properly pretreated. If your house has a termite infestation, and it is just a few years old, that might be an indication that it was improperly pretreated for termites, but this is difficult to determine.
