A pesticide injection system for exterminating insects is provided. The pesticide injection system comprises an applicator and a plug frictionally engagable with a wall. The applicator includes a pliable bottle for receiving a powder pesticide and a nozzle for injecting a powder pesticide into a blind space behind a wall suspected of harboring insects without the powder pesticide contacting the insulation. The plug has a check valve to prevent back flow and a door with a door seal to prevent the powder pesticide from spilling into a living space during use. The nozzle has a sleeve biased in a closed position by a sleeve spring for cooperatively exposing a port on the nozzle with an interlocking collar for rotatably engaging a guide on the collar and a tang on the nozzle with a flange on the plug.