IIo SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
(1906, 1907). See also Seurat (1911, 1916) and the section on 
Spirura gastrophila, p. 106. 
Gordius aquaticus Linnaeus, 1758 
Leidy (1879) identified a g-inch-long nematode found in a cock- 
roach (Blatta orientalis?) as probably being Gordius aquaticus. Stiles 
and Hassel (1894) list Blatia sp. as a host for this worm. Ransom 
(in Pierce, 1921) stated that G. aquaticus may be an accidental para- 
site of man. However, the Gordiaceae, or horsehair worms, live as 
parasites in insects until almost mature and emerge from the insects 
to become free-living adults, reproducing in water or soil (Chandler, 
1949). Although this worm may accidentally be swallowed with 
drinking water, it should not be considered a parasite of man. 
PART IV. NEGATIVE FINDINGS 
The helminths listed below are only those for which cockroaches 
have been shown experimentally not to be intermediate hosts. Nega- 
tive findings with helminths for which other cockroaches have been 
shown to be intermediate hosts are cited above. 
Cockroaches were unsuitable intermediate hosts for the following 
cestodes, or were found uninfected in nature: 
Diphyllobothrium latum (Linnaeus, 1758) Liihe, 1910 
Definitive host —Fish. 
Cockroach.—Blattella germanica. Degenerated eggs of the tape- 
worm were isolated from the insect’s rectum (Sondak, 1935). 
Hymenolepis exigua Yoshida, 1908 
Definitive host—Poultry. 
Cockroach.—Pycnoscelus surinamensis. Ten cockroaches collected 
in a poultry yard were dissected and examined for cysticercoid stages 
(Alicata and Chang, 1939). 
Hymenolepis nana (v. Siebold, 1852) Blanchard, 1891 
Defimtive host—Man. 
Cockroaches.—Neostylopyga rhombifolia, Periplaneta americana, 
and/or Periplaneta australasiae. (Morischita and Tsuchimochi, 1926.) 
