KNACK IGR (pyriproxyfen) is an insect growth regulator which was used for silverleaf whitefly, Bemisia argentifolii, (SLWF) control in AZ cotton in 1996 under a Section 18 emergency exemption registration. KNACK is a juvenoid and causes inhibition of metamorphosis, embryogenesis, reproduction, and larval development in certain insects. In SLWF, KNACK inhibits egg hatch, either through the females or by direct contact with the egg, and suppresses adult emergence when larvae stages are affected. KNACK also exhibits pronounced translaminar movement in cotton leaves which also leads to inhibition of egg hatch and suppressed adult emergence after SLWF feeding on the lower leaf surface.