If he's got critters that bad starting to attack machines... He's going to have to call a professional Bug guy like Terminix, or other local bug professional. If he explains to the bug guy what his issue if, They will drill small holes in the walls around the property so that they can spray into the foundation of the home and behind the walls...(The most logical place these critters are coming from...
There's not much else that he can do. He'll have to have the house sprayed once a year to keep up with the issue... I've been down this road many times before with family members homes...not my own..Thank Goodness.. I usually solves the issues 99% of the time..

Tony K.
Edison Collector/Restorer