Crocisa; Print; Thyreus is an Old World genus of bees; one of many that are commonly known as cuckoo bees; and are cleptoparasites of other species of bees; mostly in the genus Amegilla. They all have strongly contrasting patterns of coloration - three species from the Sydney region; Thyreus nitidulus; T. lugubris; and T. caeruleopunctatus are bright blue and black.