Natural hosts.—Pycnoscelus surinamensis, Australia (Fielding, 1926, 1927, 1928, 1928a); U.S.A. (Sanders, 1927, 1928, 1929; Shealy, 1927); Formosa (Kobayashi, 1927); Antigua (Hutson, 1938, 1943); Hawaii (Illingworth, 1931; Schwabe, 1950, 1950a, 1950b, 1951); New Caledonia (Rageau, 1956).
We have recently found (Roth and Willis, 1960) that two strains of Pycnoscelus surinamensis exist; a parthenogenetic strain (from Florida), and a bisexual strain (from Hawaii) which does not reproduce parthenogenetically. The parthenogenetic strain is undoubtedly the form that has been shown to be the host of O. mansoni in the United States and Antigua, because only this form is found in the New World. Probably the parthenogenetic strain was the form involved in most Pacific areas. However, from internal evidence in his papers, we concluded that Schwabe, in Hawaii, may well have been working with the bisexual strain and possibly also with the parthenogenetic strain; if this is true, then both parthenogenetic and bisexual strains of Pycnoscelus surinamensis may serve as intermediate hosts of the eyeworm.
Experimental hosts.—Periplaneta americana, Antigua (Hutson, 1943).
Pycnoscelus surinamensis, U.S.A. (Sanders, 1929); Australia (Fielding, 1927, 1928a); Hawaii (Schwabe, 1951).
Rictularia coloradensis Hall, 1916
Natural hosts.—Parcoblatta pensylvanica and Parcoblatta virginica, U.S.A., Ohio (Oswald, 1958): Of 49 wood roaches collected, one of each species contained a single larva each.
Experimental hosts.—Blatta orientalis, Blattella germanica, Parcoblatta pensylvanica, Parcoblatta virginica, Periplaneta americana, and Supella supellectilium, U.S.A. (Oswald, 1958): The larvae underwent normal development in all species of cockroaches except B. orientalis and P. americana in which cysts developed that contained a reddish-brown pigment; larvae in such cysts were dead or dying. Eggs of R. coloradensis hatched in the midgut of B. germanica and first-stage larvae entered the hindgut epithelium within 24 hours. The larvae underwent two molts within a cyst formed by tissues of the host's gut, the second molt occurring during the twelfth or thirteenth day. In Parcoblatta, cysts were found free in the body cavity as well as attached to the hindgut. In B. germanica and S. supellectilium the cysts remained attached to the hindgut. Usually over 20 cysts developed in each infected Parcoblatta; fewer than 10 per insect developed in the other species. Larvae became infective to the definitive host, the white-footed mouse [Peromyscus leucopus noveboracensis (Fischer)], as early as the tenth day.
Family SPIRURIDAE
* Agamospirura parahormeticae Pessôa and Corrêa, 1929
Natural host.—Parahormetica bilobata, Brazil (Pessôa and Corrêa, 1929).