Termidor is a slow-acting insecticide. This "delayed-action" effect allows insects like carpenter ants and termites, which live in colonies, time to carry some of the insecticide back to the nest where it contaminates the whole colony. This is why Termidor works well for carpenter ants as a foundation or perimeter spray because workers pick up the insecticide as they travel back and forth and thus contaminate the whole nest.
Perimeter treatments for carpenter ants can be done by many homeowners with the proper application and safety equipment. Except for spot treatments, however, treatment for termites requires equipment and expertise beyond that available to most homeowners.
The active ingredient in Termidor is fipronil. Fipronil is highly toxic to fish and aquatic invertebrates. Fipronil is toxic to bees and should not be applied to vegetation when bees are foraging
Fipronil has been found to be highly toxic to upland game birds, but is practically non-toxic to waterfowl and other bird species
Fipronil is used as the active ingredient in Frontline, a topical flea and tick control commonly used on dogs and cats. It kills adult fleas before they lay eggs.
Watch this video from a company that does not use Termidor.