As a breeder of different species of dermestid beetles, I am quite familiar with the chirping sound that the adults of some species produce. The genus Dermestes can be categorized into three subgenera. The first being the subgenus Dermestinus, whom I dubbed the “white-bellies”. The second being the subgenus Dermestes, whom I dubbed the “black-bellies”. With the third subgenus, Montandonia, I am unfamiliar.
What is interesting, is that from the two subgenera that I have studied, only the subgenus Dermestes seems to stridulate loudy and frequently (observed two species), whereas Dermestinus does not (observed four species).
There is almost no existing literature about the stridulation of Dermestes species. I have found only one scientific article from 1968 and one YouTube video about the chirping sound that the larder beetle (Dermestes lardarius) can produce. However, I might be the first to document the sound of the African larder beetle (Dermestes haemorrhoidalis) and black larder beetle (Dermestes ater).
Since both sexes stridulate and the frequency of stridulation appears to be depending on the individual, I put 15 randomly selected adult beetles of the species Dermestes Lardarius in a plastic container without any substrate together with a batlogger M in a silent room. With the same set-up, 15 randomly selected adult beetles of the species Dermestes haemorrhoidalis were also isolated and recorded. The environment and distance to the batlogger M were for both species the same. In a few hours, hundreds of recordings were made of both species.
The possibility to identify Orthoptera based on their acoustic specifications was my inspiration to record the chirps of dermestid beetles, but somehow I was still surprised to notice such a clear difference in the stridulation of both species.
I will be keen to observe and record more species in the future.
Dermestes lardarius: XC926611, XC926612, XC926610
Dermestes haemorrhoidalis: XC926616, XC926622, XC926617
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