I tried using the water from soaking dried shiitake mushrooms about 20 minutes. The mushrooms were a delicious ingredient in a dish and the water retained a faint garlicky-earthy odor. Instead of wasting it by pouring it down the drain, I used it to water some houseplants in soil. Not sure if this was a matter of perception, but a few pots with fungus gnats seemed to be cured for a while. Perhaps they may not have strict insect repelling properties, but they may have compounds that reduce the growth of competing fungi species. Shiitake mushroom derived compounds have been suggested to have anti-cancer properties on animal cells in culture. Bonaventure Magrys Cliffwood Beach, NJ USA zone 7