One hundred nine species of phytophagous insects from 6 orders and 33 families fed or reproduced on the thistle,Carduus macrocephalusDesfontaines, a biennial or winter annual in Italy. About ½ the species attacking this plant were polyphagous. Fifteen species were restricted to the tribe Cynareae; and another 16 species were restricted to the subtribe Carduniae. Only 42 of the 109 species were endophagous. Among species host specific enough to permit consideration as biological control agents, onlyPsylliodes chalcomera(Illiger),Ceuthorrhynchidius horridus(Panzer), andRhinocyllus conicus(Frolich) have been studied;Ceutorhynchus trimaculatus(F) andCheilosia grossa(Fallen) are being studied; andUrophora stolstitialis(L.),U. sibynataRondani,Cheilosia cynocephalaLoew,Epiblema pflugianaHaworth, andAgromyzan.sp. nearreptansshould be studied.