EDNOTE. Akiko tells me that Boyd has recognized the reference to the Spinx or Hawkmoth in the phrase. That l'aiguillon rouge specifically refers to the red horn sticking up on the last segment of the caterpillar.  More immediately, the  phrase refers to the receptionist's finger and nail polish as she signals HP. It is not a stinger. I have not been able to discover what its function may be. Perhaps a sex attractant?

Chenilles du "Sphinx de l'euphorbe" Celerio euphorbiae (photos M.Besnier et D.Nussbaum)

Détail de la "corne" de la chenille du "Sphinx de l'euphorbe" (photo D.Nussbaum)