The name of the taxonomic order, Coleoptera, comes from the Greek koleopteros (κολεόπτερος), given to the group by Aristotle for their elytra, hardened shield-like forewings, from koleos, sheath, and pteron, wing.

[29] A 2020 review of the palaeoecological interpretations of fossil beetles from Cretaceous ambers has suggested that saproxylicity was the most common feeding strategy, with fungivorous species in particular appearing to dominate.

[39] Lower Cretaceous sites include the Crato fossil beds in the Araripe basin in the Ceará, North Brazil, as well as overlying Santana formation; the latter was near the equator at that time.

The large oscillations in climate during the Quaternary caused beetles to change their geographic distributions so much that current location gives little clue to the biogeographical history of a species.

It is evident that geographic isolation of populations must often have been broken as insects moved under the influence of changing climate, causing mixing of gene pools, rapid evolution, and extinctions, especially in middle latitudes.

[10][47] These polyphagan beetle groups can be identified by the presence of cervical sclerites (hardened parts of the head used as points of attachment for muscles) absent in the other suborders.

[53] The consistency of beetle morphology, in particular their possession of elytra, has long suggested that Coleoptera is monophyletic, though there have been doubts about the arrangement of the suborders, namely the Adephaga, Archostemata, Myxophaga and Polyphaga within that clade.

[77] The abdomen is the section behind the metathorax, made up of a series of rings, each with a hole for breathing and respiration, called a spiracle, composing three different segmented sclerites: the tergum, pleura, and the sternum.

[8] To attract a mate, fireflies (Lampyridae) use modified fat body cells with transparent surfaces backed with reflective uric acid crystals to produce light by bioluminescence.

The males and females engage in a complex dialog before mating; each species has a unique combination of flight patterns, duration, composition, and intensity of the light produced.

Furthermore, these physical properties of the thistle tortioise beetle have been studied because the ability of a thin, flexible structure to harden without buckling or rupturing is mechanically challenging and may have important implications for the development of microscopic catheters in modern medicine.

The larvae of skin beetles undergo a degree of reversed development when starved, and later grow back to the previously attained level of maturity.

In some species, sculpturing or various colored scales or hairs cause beetles such as the avocado weevil Heilipus apiatus to resemble bird dung or other inedible objects.

The defensive glands of carabid ground beetles produce a variety of hydrocarbons, aldehydes, phenols, quinones, esters, and acids released from an opening at the end of the abdomen.

The beetle families that habitually pollinate flowers are the Buprestidae, Cantharidae, Cerambycidae, Cleridae, Dermestidae, Lycidae, Melyridae, Mordellidae, Nitidulidae and Scarabaeidae.

The beetles cannot eat the wood due to toxins, and uses its relationship with fungi to help overcome the defenses of its host tree in order to provide nutrition for their larvae.

To endure the period without food (often lasting many months) adults prepare by accumulating reserves of lipids, glycogen, proteins and other substances needed for resistance to future hazardous changes of environmental conditions.

[133] A study of hibernation in the Arctic beetle Pterostichus brevicornis showed that the body fat levels of adults were highest in autumn with the alimentary canal filled with food, but empty by the end of January.

[137] At these low temperatures, the formation of ice crystals in internal fluids is the biggest threat to survival to beetles, but this is prevented through the production of antifreeze proteins that stop water molecules from grouping together.

[139] The Alaskan beetle Upis ceramboides can survive −60 °C: its cryoprotectants are xylomannan, a molecule consisting of a sugar bound to a fatty acid,[140] and the sugar-alcohol, threitol.

These beetles also exhibits behavioural adaptions to tolerate the heat: they are able to stand erect on their tarsi to hold their bodies away from the hot ground, seek shade, and turn to face the sun so that only the front parts of their heads are directly exposed.

[143] The fogstand beetle of the Namib Desert, Stenocara gracilipes, is able to collect water from fog, as its elytra have a textured surface combining hydrophilic (water-loving) bumps and waxy, hydrophobic troughs.

[145] Anoxia tolerance in the adult carabid beetle Pelophilia borealis was tested in laboratory conditions and it was found that they could survive a continuous period of up to 127 days in an atmosphere of 99.9% nitrogen at 0 °C.

To these insects a sting has been denied by Nature; but in one large kind we find horns of a remarkable length, two-pronged at the extremities, and forming pincers, which the animal closes when it is its intention to bite.

[175][176] Dung beetles (Scarabidae) have been successfully used to reduce the populations of pestilent flies, such as Musca vetustissima and Haematobia exigua which are serious pests of cattle in Australia.

[177] The American Institute of Biological Sciences reports that dung beetles, such as Euoniticellus intermedius, save the United States cattle industry an estimated US$380 million annually through burying above-ground livestock feces.

Whole beetles, either as-is or encased in clear plastic, are made into objects ranging from cheap souvenirs such as key chains to expensive fine-art jewellery.

[199] The naturalist Alfred Russel Wallace collected (by his own count) a total of 83,200 beetles during the eight years described in his 1869 book The Malay Archipelago, including 2,000 species new to science.

[201] Moisture harvesting behavior by the Namib desert beetle (Stenocara gracilipes) has inspired a self-filling water bottle which utilises hydrophilic and hydrophobic materials to benefit people living in dry regions with no regular rainfall.

In Japan the Genji firefly, Luciola cruciata, is extremely popular, and in South Africa the Addo elephant dung beetle offers promise for broadening ecotourism beyond the big five tourist mammal species.