The major component of the male or female dorsal abdominal gland secre
tion of the aposematic shield bug, Cantao parentum (White) (Hemiptera:
Scutelleridae), is R,8S)-2,4,8-trimethyl-1,7-dioxaspiro-[5.5]undecane
(23), the first example from the insect kingdom of a branched carbon
chain spiroketal and the first spiroketal of any type from Hemiptera o
r lower insect orders.