Bio Spot for Cats Stripe-On 6/mo Farnam. Contains permethrin and Nylar (insect growth regulator). It kills and repels fleas, ticks, and mosquitoes for up to 3-4 weeks, prevents flea eggs form developing into biting adults for up to 123 days, protects against blood feeding mosquitoes (vector fo heartworm) for up to 4 weeks, breaks the flea life cycle by killing more that 92% of fleas within 1 day and kills on contact so fleas do not bite.