By the window of a country house I found two celeoptera performing an incomprehensible dance for me: the female was licking the tip of the male’s elytra (the picture shows this instant) while the male gets
behind the female with the apparent intention of copulating. I think the tiny couple are Ebaeus collaris. How is the sexual life of these
malachites? How is their behaviour explained, which any human unaware of its reason may call oral sex?
Question sent by CONSUELO VENTO MARTI (Valencia). SERGIO MONTAGUD answers:
First of all, I would like to congratulate Consuelo for her entomological skills. Knowing that the animals she was observing were malachites and recognizing them as belonging to the Elbaeus collaris Erichson, 1840 species, is not within everybody’s reach. These small beetles are barely 5 mm long, and there are many similar species, from their own family and others. The behaviour you have observed in these beetles is very interesting because their group— the malachite family— is the only one that performs it.
This behaviour, which has been so surprising, is a part of the usual precopulatory rituals of many malachites, some Pyrochroidae and Anthicidae (all of them beetles). All along their bodies, males have a series of well-innervated integumentary glands which specialists have named «excitators». During courtship, the male exposes them to the female and segregates substances which are licked by the female. It appears that these substances, composed of pheromones, act in different ways. On the one hand they stimulate the male to initiate intercourse, and on the other hand they increases the female receptivity.
Excitators can be located in different areas of the body, depending on the species. In Ebaeus they are located at the tip of the elytra. They are folds with a characteristic shape in the integument, where the aforementioned glands come out onto. Therefore, unfortunately, it is not correct to call it “oral sex” as Consuelo indicated. But it is not that away from our mundane fantasies. We could compare it to a kind of magic potion, elaborated by the male with care, great precision and tenderness so as to, when the time comes, pay homage to his lady.
Sergio Montagud. Biologist, Valencia.