How do you apply permethrin for mosquito repellant?

With care. Permethrin acts as a neurotoxin with greater effects on cold-blooded creatures like insects, fish, reptiles than warm- blooded. Overdoses can cause nausea, headaches, muscle weakness, excessive salivation and seizures. It has been classified by the epa as a likely human carcinogen. Thus, use sparingly and not around highly absorbable surfaces like any mucous membranes (nose, eyes, mouth).