The cochineal insects include nine species assigned to the genus Dactylopius Costa, 1835, the only genus in the family Dactylopiidae. The present research is a comprehensive review of all the species in the family Dactylopiidae, with special emphasis on the life cycle of the type species Dactylopius coccus Costa. The adult females of the nine species have been redescribed and illustrated in detail, with a discussion on their morphological affinities and relationships. Their hosts, natural enemies, distribution, etymology, and role as biological control agents are discussed. For several species many new distribution and host records are given. Also, new types have been designated for some of the species. These included designation of one neotype and three paratypes for Dactylopius coccus Costa, one neotype for D. tomentosus (Lamarck), and designation of eight new topotypes for D. opuntiae (Cockerell). Methods are given on collecting, preservation and slide mounting, also on measurements and on preparation of illustrations. Cuticular ultrastructure is shown in scanning electron micrographs. All developmental stages of the type species D. coccus are described. The life cycles under two temperatures and relative humidities, for both males and females are discussed. Aspects of reproduction in D. coccus, its dispersal methods, factors affecting development, and its economic importance are also included. A separate chapter deals with the host-plants of Dactylopiidae. This includes data on host plant suitability and host plant resistance. Three identification keys are presented: one to the suborders of Homoptera, the other to the superfamilies and families of Coccinea, and another one for the determination of the species of Dactylopius. The phylogenetic relationships of the family Dactylopiidae with respect to all the Coccinea families is discussed. A phylogenetic tree for the Dactylopius species is proposed. / Ph. D.