Fipronil is a broad spectrum insecticide that disrupts the insect central nervous system by blocking the passage of chloride ions through the GABA receptor and glutamate-gated chloride channels (GluCl), components of the central nervous system. This causes hyperexcitation of contaminated insects' nerves and muscles.
Fipronil is a slow acting poison. When mixed with a bait it allows the poisoned insect time to return to the colony or harborage. In cockroaches the feces and carcass can contain sufficient residual pesticide to kill others in the same nesting site. In ants, the sharing of the ant bait among colony members assists in the spreading of the poison throughout the colony. With the cascading effect, the projected kill rate is about 95% in 3 days for ants and cockroaches.
Products such as Maxforce FC Roach Bait, Maxforce FC Ant Bait, and Termidor contain Fipronil. These pest control products work so well because the fipronil is non repelling and allows the insects to move into the area without the chemical being detected.