Sawyer Picaridin 20% Insect Repellent, also known as “the fisherman’s formula,” is similar to DEET but is much more effective on flies and won’t harm gear or equipment. Sawyer Picaridin 20% Insect Repellent is a long-lasting topical repellent that’s effective up to 8 hours against mosquitoes, ticks, chiggers, fleas, gnats, and biting flies. Because Sawyer Picaridin 20% Insect Repellent is DEET-free, it is great for children.