Rhinoceros Beetle

Rhinoceros beetles are large, heavy-bodied beetles named for the horns that many males carry on their heads, just like a rhinoceros. They are a group of scarab beetles in the subfamily Dynastinae, which contains around 1,500 species. Some of them, like the Hercules beetle, are among the biggest beetles on Earth.

Rhinoceros beetle Quick Facts

Common name	Rhinoceros beetle
Type	Insect (scarab beetle)
Diet	Larvae eat rotting wood and compost; adults eat sap, nectar and fruit
Habitat	Forests, rainforests, gardens and compost heaps
Native range	Worldwide except Antarctica; most species in the tropics
Size	Most a few cm; Hercules beetle males up to about 17 cm
Lifespan	Often 1-3 years, mostly spent as a grub; adults live a few months
Special feature	Males have horns used for wrestling rivals

Where Do Rhinoceros Beetles Live?

Rhinoceros beetles live on every continent except Antarctica, but they are most varied in warm, tropical places such as the rainforests of Central and South America, Africa and Southeast Asia. In the United States, the eastern Hercules beetle lives in eastern forests, and in Australia, the rhinoceros beetle Xylotrupes is a familiar summer visitor in places such as Brisbane. In the tropics, adults can be found for much of the year.

What Do They Look Like?

Rhinoceros beetles are usually shiny and dark brown, black or reddish, though a few are olive, yellowish or even greenish. They have tough, rounded bodies and strong legs with hooked claws for gripping.

Most species are a few centimeters long. The record-holders are:

• The Hercules beetle (Dynastes hercules) of Central and South America, whose males can reach about 17 cm (almost 7 inches), including their very long horn.
• The atlas beetle and elephant beetles, other giants with large horns and bulky bodies.

Usually only the males have big horns. Depending on the species, they may have one horn on the head, or one on the head plus one or more on the thorax. Females have small bumps or no horns at all. Even within one species, well-fed males grow bigger horns than males that had less food as larvae.

What Are the Horns For?

Male rhinoceros beetles use their horns to fight other males for the best feeding spots and for the chance to mate with females. They try to push, lift or flip their rival off a branch, rather like tiny wrestlers. The horns are not used to attack people, and rhinoceros beetles cannot sting.

Rhinoceros beetles are also famously strong. In lab tests, some have carried loads many times their own body weight. That is a little like a person carrying a car on their back.

What Do They Eat?

The larvae, which are fat, C-shaped white grubs, live in rotting logs, compost and leaf litter. They feed on decaying wood and plant material, helping to break it down and recycle nutrients into the soil.

Adults feed on plant sap, nectar, tree sap oozing from wounds, and soft, rotting fruit. Some adults eat very little during their short lives.

Life Cycle

Rhinoceros beetles go through complete metamorphosis: egg, larva, pupa and adult.

• Eggs: After mating, the female lays her eggs in rotting wood, compost or soil rich in decaying plants. Depending on the species, she may lay dozens of eggs. They hatch after a few weeks.
• Larvae: The grubs feed and grow, molting twice through three larval stages. This is by far the longest part of the life cycle, lasting from several months to two years or more in large species.
• Pupae: The fully grown grub builds a chamber in the soil or wood and turns into a pupa, a stage that lasts a few weeks.
• Adults: New adults may stay underground for a while before digging out. They usually live for a few months, often less.

Many rhinoceros beetles are active at night and are sometimes attracted to lights. Females release special scents called pheromones that help males find them.

Rhinoceros Beetles as Pests

Most rhinoceros beetles are harmless and even helpful, because their grubs recycle dead wood. A few species, however, damage crops. The most serious is the coconut rhinoceros beetle (Oryctes rhinoceros), native to Southeast Asia.

Adult coconut rhinoceros beetles bore into the crown of coconut and other palms, feeding on the soft, growing tissue and sap. This damages the leaves, reduces coconut harvests, and can kill young palms. The beetle has spread to many Pacific islands. It was discovered in Hawaii in December 2013, where it has become a serious invasive pest.

To control it, people:

• Remove or cover breeding sites, such as piles of rotting logs, green waste, compost and dead palm trunks.
• Use traps baited with the beetle’s own scent.
• Release natural diseases, such as a virus and a fungus that infect the beetles, in some places.
• Inspect plants, soil and green waste before moving them to new areas.

Fun Facts

• In Japan, the Japanese rhinoceros beetle, called kabutomushi, is a popular pet, and children often keep them in summer.
• In some parts of Asia, people even hold friendly beetle-wrestling contests between males.
• Some rhinoceros beetles make a hissing or squeaking sound when disturbed, by rubbing parts of their body together.

Related: palm trees

Rhinoceros beetle FAQs