Burrowing trends and bioturbation rates of the May beetle or cockchafer Melolontha melolontha were estimated from a wild-caught larval specimen in Poland in September 2020. It was housed in a custom-made 0.55-cm-thick glass-paned container, filled to an area of around 21 cm × 26.5 cm with alternating sand layers (3.1 to 8.6 mm thick) composed of blue-, pink- and yellow-coloured aquarium sand (x̄, mean = 0.57 mm, σ, standard deviation = 0.18 mm; the grain size was chosen to be similar to that of sand in dune habitats where the living species as well as some subfossil bioturbation traces had been found). It was photographed at points between September 11 and 25, 2020, starting after the larva was placed into the container and had already made a small initial burrow with the first observation (0 h) on September 11, at 12:06 pm. Measurements of the area disrupted cumulatively in a vertical section of sediment (comparable to the ichnofabric index) were taken based on the photographs and used to calculate bioturbated volume by multiplying by the container thickness. For each point, the total cumulative area of visibly bioturbated (i.e. noticeably transported or mixed, as observed from colour contrast) sand was calculated by digital tracing with CorelDRAW and area measurement with the software ImageJ. Filming of how the larva burrowed was also done, and the observations were briefly compared to previous studies.
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