I am not able to trace any research article particularly on Conocephalus discolor, though there are few papers for other Conocephalus variants but not of much use.
I found out that there is one more paper concerning Conocephalus fuscus (discolor) egg development.
Please find it attached, together with the paper Nadine mentioned, if that would help.
Papers' titles are: Y. Ando & J. C. Hartley (1982) Occurrence and biology of a long-winged form of Conocephalus discolor. Entomologia Experimentalis et Applicata. 32 (3) 238-241.
J. C. Hartley & A. C. Warne (1972) The developmental biology of the egg stage of Western European Tettigoniidae (Orthoptera). Journal of Zoology. 168 (3), 267-298.