Insects have evolved various adaptations that allow them to survive adverse seasons. In terms of cold-hardiness, they may classically be divided into freezing-susceptible versus freezing-tolerant species. But this concept of two alternative cold-hardiness strategies is now amendable, and to better understand these adaptive mechanisms, it is of interest to study freezing resistance in taxonomically related insect species, i.e., belonging to the same family or to a group of closely related organisms sharing similar resources. Freezing susceptibility and freezing tolerance have previously been recorded in the larvae of species in the same guild of the family Cetoniidae, which mainly colonise wood mould in hollow trees. We compared freezing hardiness in five species of Cetoniidae, three species in the subfamily Trichiinae, Gnorimus nobilis (Linné), Trichius fasciatus (Linné), and Osmoderma eremita (Scopoli), and two species in the subfamily Cetoniinae, Cetonia aurata (Linné) and Cetonischema aeruginosa (Drury). Our results mainly show that two contrasting mechanisms are used during winter by third-instar larvae: those of the Trichiinae (apart from O. eremita) are probably characterized by year-round freezing susceptibility, and those of O. eremita and the Cetoniinae are probably distinguished by seasonal freezing susceptibility (summer) and seasonal freezing tolerance (winter). We question the current taxonomic position of the genus Osmoderma. Morphological, ecological, and behavioural arguments may be put forward to support the transfer of O. eremita from the Trichiinae to the Cetoniinae, and we stress that ecophysiological arguments, often neglected in this kind of taxonomic revision, must also be taken into account.