Fig. 2. In vitro hydrocarbon biosynthesis by embryos (A), first-instar nymphs (B) and newly molted second-instar nymphs (C) of B. germanica. Forty embryos in a single egg case or 40 individual nymphs were bisected with a sharp razor and incubated for 3 h in a medium fortified with sodium [1-¹⁴C]propionate. The tissues and medium were extracted in chloroform/methanol/water and the hydrocarbons were then purified on silica gel and quantified by LSS. Data are means ± s.e.m. (N=8).