INTRA-UTERINE NUTRITION OF 
THE “BEETLE-ROACH” DIPLOPTERA DYTISCOIDES 
(SERV.) 1 DURING EMBRYOGENESIS, WITH NOTES 
ON ITS BIOLOGY IN THE LABORATORY 
(BLATTARIA : DIPLOPTERIDAE) 
By Louis M. Roth and Edwin R. Willis 
Pioneering Research Division 
U. S. Army Quartermaster Research 
and Development Center 
Natick, Massachusetts 
Diploptera dytiscoides is a common viviparous cockroach 
that injures the bark of several kinds of trees in Hawaii 
and other Pacific Islands (Fullaway and Krauss, 1945). 
Its embryology has been extensively studied by Hagan 
(1951) who indicated that the embryo increases over five 
times in size during development. This growth was not 
accompanied by a decrease in yolk, and Hagan suggested 
that the developing embryo acquired nutriment from an- 
other source. The embryos have greatly elongated pleuro- 
podia to which Hagan (1939, 1951) tentatively ascribed 
nutritional or respiratory functions, or both. Because of 
the embryo’s increase in size and its modified pleuropodia, 
Hagan (1951) cited D. dytiscoides as the one example of 
pseudoplacental viviparity among cockroaches. Although 
Hagan’s suggestion is a logical hypothesis, the acquisition 
of nutriment by the embryo has never been examined 
experimentally. 
The eggs of the false ovoviviparous cockroach, Nau- 
phoeta cinerea (Oliv.), also increase in size during em- 
bryogenesis ; this increase is closely correlated with absorp- 
tion of water, whereas solids are slowly lost until hatching 
(Roth and Willis, 1955). In order to determine whether 
'We are greatly indebted to the United States Department of Agri- 
culture for permission to import this species, and to Mr. Fred A. Bianchi 
of the Hawaiian Sugar Planters Association, who kindly sent us several 
hundred living specimens of Diploptera. The insects were cultured on 
Purina dog chow checkers. 
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