The milbemycins comprise a group of natural products isolated from cultures of Streptomyces B-41-146, of which milbemycin p3 (1) is the simplest.1 Interest in these com- pounds has increased since the isolation and identification of a structurally related series of macrolides, the avermectins.' ... The avermectins are effective against helminths and arthro- pods at very low concentrations, giving these compounds enormous potential as broad spectrum anti- ...
