Propylene glycol in water is a safe and effective alternative to ethylene glycol as a capture liquid in insect traps (pitfalls, flight intercepts, pan traps). Propylene glycol formulations are readily available because it is the primary (95%) ingredient in certain automotive antifreeze formulations. However, an even safer and less expensive alternative is the USP food grade RV antifreeze used for winterizing drinking water systems. The automotive formulations contain additives (about 5%) that contribute to the cost and involve safety, environmental, and waste disposal issues. Using bacterial inhibition as an indicator, the preservational attributes of the automotive and RV antifreeze were found to be comparable in laboratory tests. Entomologists are urged to use nontoxic antifreeze in their trapping programs.