Pest Expert Formula 'C+' Cluster Fly Spray is a fast-acting cluster fly killer with a long-lasting residual that helps maintain cluster fly control. Our latest innovative formulation incorporates two additional active ingredients. The first is pyriproxyfen, a ground-breaking insect growth regulator that halts the progression of the lifecycle development from juvenile to adult, resulting in the inability for the fly to reproduce. The second is the addition of chrysanthemum cinerariaefolium extract, a natural pyrethrum, which when combined with cypermethrin (0.1%) has a synergistic effect, helping to deliver an even faster knockdown and longer-lasting residual for ongoing control of all lifecycle stages. Pest Expert Formula 'C+' is the most powerful cluster fly killer spray available to the amateur market, offering both fast-acting and long-lasting cluster fly control to help you eradicate a cluster fly infestation in your home, loft or roof space. Formula 'C+' Cluster Fly Spray should be applied to any alighting surfaces including window frames and roof timbers. Formula 'C+' is water-based and low-odour, making it perfectly suitable for use in homes with children and/or pets, provided they are kept out of the area being treated until all surfaces are dry (2-3 hours).