[2][3][4][5] It is a solitary bee that nests in holes or stems and is polylectic, meaning it forages pollen from various different flowering plants.

These bees are not aggressive; they will only sting if handled very roughly and are safe to be closely observed by children.

Subsequently, the opinion was put forth that A. rufa was the correct name, because it appeared before bicornis in the Systema Naturae.

Additionally, these bees make their nests in such sites as sandy banks, decaying trees planted in clay soil like the willow tree, old-mortared walls, flint stone holes, garden shed fifes[clarification needed], and window frame holes and cracks.

[14] The nest of O. bicornis consists of an array of partitioned cylindrical cells[15] in holes in wood or reed tubes.

If the internal diameter of the tube exceeds 12 mm, then this linear arrangement may be forced into two rows instead of one.

[15] Cells containing females are typically larger than those containing males, due to the sexual dimorphism of the species.

Due to the linear arrangement of cells in the nest, the youngest bee leaves earlier than older ones.

[8] The adults then hibernate through the winter in the cocoons and finally emerge as mature bees in the spring.

[22] These bees store mostly pollen moistened with a small amount of nectar,[5] which is eaten by the larvae during the summer before they rest through the winter in a cocoon.

A similar colour system is found in these bee species: Apis mellifera, Bombus terrestris, B. lapidarius, B. monticola, B. jonellus, Vespula germanica, and V. vulgaris.

Studies comparing the colour systems of O. bicornis and A. mellifera show both species share the same spectral sensitivity functions in ultraviolet and blue receptors, while the green receptor in O. bicornis is sensitive to longer wavelengths than in A. mellifera [7] During mating season, male behaviour with respect to pursuing females is varied, with some males establishing territories close to nesting sites where females emerge and other males observing flowering sites nearby.

To counteract these difficulties, males can increase their mating chances by positioning themselves close to foraging sites.

[25] O. bicornis females attract males through sex pheromones,[26] which are localized on their cuticle surfaces.

During what is called the precopulatory phase, the male rubs the female's mesothorax with his first two pairs of legs.

Every stroking motion is recognizable to humans as a high-pitched humming sound, which soon turns into buzzing as the male attempts to copulate.

At this time, the male applies an antiaphrodisiac on the female by stroking his abdomen over her in the posterior to anterior direction.

[28] Typically in adult insects, reproductive diapause is characterized by a late development of gonads and a buildup of energy reserves.

The ovaries of females are not completely inactive during overwintering, as the development of oocytes continues in the vitellarium region.

[30] O. bicornis has shown a strong inclination towards collecting pollen from maple and oak trees, like most other solitary bees.

Since maple and oak pollen have similar protein content (with a deviation up to 5%), larvae reared on the diet of either plant do not differ in cocoon weight – hence the offspring of O. bicornis develop equally on the pollen of both zoophilous and anemophilous plants.

When oak and maple are no longer in bloom, the bees tend to forage on pollen from poppy and buttercup plants.

Larvae decrease their food intake as the temperature rises and start cocoon-spinning earlier, resulting in smaller body mass.

[11] A majority of the pollen these bees consume comes from Ranunculus acris, R. bulbosus, R. repens, and Quercus robur flowering species.

[32] Both C. indagator and A. anthrax lay their eggs while the O.bicornis female adds food to the nest cells.

[30] For instance, C. indagator, a member of the family Drosophilidae, may be found in nest cells eating pollen.

The organism's activity sometimes results in the bee larvae dying from a lack of sufficient food.

The older a bee gets, the longer its provisioning time takes, due to the wearing out of the exoskeleton, wings, and pollen-collecting apparatus, as well as the aging of muscles used for flight.

Additionally, since sexual dimorphism in the bees gives rise to larger female offspring than male, mothers can choose to fertilize the egg to produce a daughter earlier in the season (i.e. when they are able to forage most efficiently (and a son later).

Protein components in the venom, such as osmin, have been linked to antimicrobial, antifungal, and haemolytic activities.