When used monthly, Frontline Plus completely breaks the flea life cycle and control tick and chewing lice infestations. Do not reapply Frontline Plus for 30 days. Frontline Plus kills adult fleas, flea eggs, and flea larvae for up to six weeks. Frontline Plus also prevents development of all flea stages for up to six weeks. Frontline Plus can control fleas for up to six weeks, however, if there is a high risk of reinfestation or if the cat has fleas which may cause flea allergy dermatitis, a once monthly application may be needed.