No, these termites and our native termites are not resistant to any insecticides. On average, one Formosan termite worker is the same as a native subterranean termite worker. A bigger problem with Formosan termites is their potential colony size. Researchers often find that these colonies are larger than native subterranean termite colonies. It is possible to have Formosan subterranean termite colonies with several million workers.
More workers means more individuals can feed on a structure at a given time.
It also means that more individuals may be tunneling and foraging around a building, providing an increased chance of Formosan termites finding a weakness in a termite treatment. They can, but not as often as most people think. In Charleston an intensive survey of 50 structures infested with Formosan termites showed that 94 percent of the buildings were infested from ground-based colonies. Only six percent were infested by aerial colonies. An above-ground moisture source was the key component for Formosan subterranean termites to establish an aerial nest.