The answer to 'when to treat for fumigation' is that fumigation is typically required when there is a severe pest infestation that cannot be controlled with other methods. Fumigation is a comprehensive treatment that involves releasing toxic gases into a sealed space to eliminate all stages of pests, including eggs and larvae. It is often used for infestations of termites, bedbugs, or other hard-to-control pests.
Fumigation should be considered as a last resort when other pest control methods have failed. It is a complex and dangerous process that requires professional equipment and training, so it should only be performed by licensed and experienced pest control technicians. Homeowners should never attempt to fumigate their own homes, as it can be extremely hazardous if not done properly.