none Females of the solitary endoparasitic wasp Biosteres longicaudatus sometimes deposit > 1 egg (superparasitism) in each larva of the Caribbean fruit fly host, Anastrepha suspensa. As host density increases, there is an inverse relationship between the level of superparasitism and the number of progeny produced/female. Larval parasitoid competition in superparasitized hosts causes an abrupt decline from > 1 to 1 or < 1 parasitoid/host 24-36 h before the surviving parasitoid larva molts to the 2nd instar. The mechanism by which supernumaries are eliminated was investigated by indirect, in vivo and direct, in vitro methods.