The insect repellent of choice for outdoor experts The active ingredient in REPEX is DEET – (N, N. Diethyl-meta-toluamide) was developed and tested by the U.S. Department of Agriculture, and introduced to Canada by STANLEYKEM INC. in 1957. The choice is yours… Choose REPEX Insect Repellent in the form that suits you best. HM95 REPEX liquid 50 ml 30% DEET. REPEX full strength REPEX for maximum protection in severe insect conditions. HM23 REPEX Aerosol Spray 140 g. 23,75 % DEET. Convenient spray can for quick application to skin and clothing. HM45 REPEX Pump Spray 114 ml., 30 % DEET. Convenient spray pump for quick application to skin and clothing.