Chlordane is a chlorinated hydrocarbon that was used widely for termite control under name of Velsicol. It worked very well. Re treats were almost non existant. Unfortunitely, it worked to well and was removed from the market in 1986. The product would last around 30 years in the soil. That means that many homes protected by the termiticide are now subject to reinfestation. If you see active termites, swarmers and mud tunnels you will need another treatment. Today Termidor is the very best product to eliminate the colony.