[8][9] Adult horned fungus beetles are active at night, but may be found during the day on the undersides of their host fungi.

Male beetles will find and defend a piece of fungus they deem to be good for offspring.

Females are limited in how many offspring they can have by how big the fungus is, causing them to select males with larger pieces of fungi.

This leads to male-male fighting over fungal brackets, as a male wants the largest fungus in order to attract females.

Eggs are only laid between June and August, which leads to a very limited number of offspring depending on how often females mate.

Post-hatching, the larvae take 5 days before they leave their egg capsules and go into the fungus they were laid upon.

[12] Bolitotherus cornutus adults perform reproductive behaviors on the surfaces of fruiting bodies of their host fungus.

[8] Mating pairs engage in a courtship ritual in which the male grips the female's elytra, with his thorax over the end of her abdomen.

During a copulation attempt, the male reverses position on top of the female so that both individuals point the same direction and their abdomens are aligned.

If the courtship is successful, the female opens her anal sternite and copulation takes place.

When the eggs hatch, the larvae burrow into and consume the fungus, in which they later pupate before emerging as adults.

Females have the ability to selectively open and close their anal plate in order to entirely physically block males.

It is not directly linked to each individual sperm packet being larger, but over time there is significant data.

These larger sperm packets over time mean that older beetles are more likely to father offspring.

Larva themselves are protected firstly by their egg capsules and then by the fungus they live and develop within when they hatch.

Oftentimes, these pupa are attacked or consumed by larval siblings or by other forked fungus beetle larva.

There is evidence of the larva potentially attacking and consuming one another, however, larval cannibalism of pupa has been experimentally observed.

[12] Once the pupa has matured into an adult beetle, the socialization between individuals of this species diminishes until reproduction.

The majority of the fungus beetle's defenses are designed to fight against other members of the same species for reproductive purposes.

Due to the stationary nature of their life, it is also incredibly common for mammals to both purposefully and accidentally try to consume them.

Rodents often predate on the beetle, ranging from small pocket mice to even large ground squirrels.

However, adult female braconid wasps themselves will often attack larva of the forked fungus beetle.