Darkling Beetles (lat. Tenebrionidae)

Taxonomy

Tenebrio is the Latin generic name that Carl Linnaeus assigned to some flour beetles in his 10th edition of Systema Naturae 1758–59. The name means “lover of darkness”; the English language term ‘darkling’ means “characterised by darkness or obscurity”; see also English ’tenebrous’, figuratively “obscure, gloomy.” Many Tenebrionidae species inhabit dark places; in genera such as Stenocara and Onymacris, they are active by day and inactive at night. The family covers a varied range of forms, such that classification presents great difficulties. These eleven subfamilies were listed in the 2021 review by Bouchard, Bousquet, et al., updating a similar catalog from 2005.

Alleculinae Laporte, 1840 Blaptinae Leach, 1815 Diaperinae Latreille, 1802 Kuhitangiinae G.S. Medvedev, 1962 Lagriinae Latreille, 1825 Nilioninae Oken, 1843 Phrenapatinae Solier, 1834 Pimeliinae Latreille, 1802 Stenochiinae Kirby, 1837 Tenebrioninae Latreille, 1802 Zolodininae Watt, 1975 Ongoing phylogenetic studies are showing that some taxonomic changes are needed. For instance the tribal classification of tribe Pedinini has recently been altered. The misspelling “Terebrionidae” occurs frequently enough to be easily overlooked. The error appears to have no particular significance, but to be the product of misreadings, mis-scans and mis-typings.

The oldest known member of the family is Jurallecula from the Late Jurassic Karabastau Formation of Kazakhstan, assigned to the subfamily Alleculinae.

Biology and ecology

Tenebrionid beetles occupy ecological niches in mainly deserts and forests as plant scavengers. Most species are generalistic omnivores, and feed on decaying leaves, rotting wood, fresh plant matter, dead insects, and fungi as larvae and adults. Several genera, including Bolitotherus, are specialized fungivores which feed on polypores. Many of the larger species are flightless, and those that are capable, such as T. molitor, often rarely do so.

The larvae, known as mealworms or false wireworms, are usually fossorial, heavily sclerotized and nocturnal. They may possibly be an important resource for certain invertebrates and small mammals. Adults of many species have chemical defenses and are relatively protected against predators. Adults of most species, except grain pests, have slow metabolisms, and live long lives compared to other insects, ranging from approximately six months to two years. Some species live in intensely dry deserts such as the Namib, and have evolved adaptions by which they collect droplets of fog that deposit on their elytra. As the droplets accumulate the water drains down the beetles’ backs to their mouthparts, where they swallow it. Humans spread some species such that they have become cosmopolitan, such as Tribolium castaneum, the red flour beetle, which was spread through grain products.