Pest Expert Formula C+ Advanced Cluster Fly Killer Spray is the new and improved formulation of our bestselling ready-to-use triple action cluster fly killer, with a long-lasting residual that maintains cluster fly control for up to 12 weeks. Its unique combination of actives make it the most powerful cluster fly spray available to the amateur market, and the ultimate insecticide for anyone wanting fast and effective eradication of any size cluster fly infestation. This 1L canister will treat up to 50 sq m in a single application.