A caution re the post immediately above.
Permethrin is an effective insect control treatment for many insects including lice and mites and is widely used in agricultural applications.
However, resistance to it's effectiveness can develop with frequent use. The use in compost can negatively affect cats, as stated and. in addition, "Water contamination by pesticides is known to induce harmful impacts on the production, reproduction, and survivability of living aquatic organisms, such as algae, aquatic plants, and fish (shellfish and finfish species)." (National Library of Medicine).
In general, the use of permethrin and other insect control treatments should only be used in response to specific and identified infestations that cannot be treated in other ways (eg to eradicate flies when other means of control such as removal of waste are available).