More effective at repelling biting flies than DEET, it's also effective at repelling stable flies, black flies, gnats, chiggers, and sand flies. Sawyer 20% Picaridin topical spray is effective for up to 12 hours against mosquitoes and ticks (14 hours for the lotion), and the spray and lotion provide up to 8 hours of protection against biting flies, gnats, chiggers, and sand flies.