Tok-tok beetles are one of those insects that form part of childhood memories. They are commonly seen during the day, walking boldly along paths. Their broad, almost bulbous abdomen makes them easily recognisable. But it is when they stop and use that overweight rear end to tap the ground with rythmic beats that they become an enduring memory. To see them performing this strange ritual engages both child and adult alike in the simple delights of nature. Even more fun, is to see if one can repeat the pattern oneself on a suitable stone and participate with the beetle in a tok-tokking competition.
Tok-tok beetles belong to the beetle family Tenebrionidae, a large cosmopolitan group with over 3,500 species in Southern Africa alone. The toktokkies are found in two particular genera, Psammodes and Dichtha. The common tok-tok beetle here in the south-western Cape is Psammodes striatus or Striped Toktokkie. The abdomen of this species is predominantly black with dark brown longitudinal stripes. The beetles feed on a variety of plants and even animal matter. They are large, slow and flightless and would therefore appear vulnerable to predators. They must either be distasteful or have some other mechanism to defend themselves.
While tok-tokking is a reportedly part of the mating process, attracting a suitable mate, it was not immediately obvious that this is what the two beetles of Psammodes striatus I observed were doing. They had clearly drawn attention to each other already but were now keeping a safe distance apart and drumming the ground alternately. It appeared like a dominance behaviour between two males; a testing out who had the loudest, hardest tap. Admittedly, it might well have been courtship but that the female was holding out to check that the male was tapping his hardest. Considering the familiarity of these beetles, we still understand so little about these wonderful creatures.
You can watch the full video here: https://www.youtube.com/watch?v=LAlQzrLfh3Q