Rhinoceros Beetles

Rhinoceros beetles are beetles that fall under the subfamily Dynastinae. They are sometimes referred to as Hercules beetles, horn beetles, or unicorn beetles. They are known for their impressive size and unique physical appearance, including the large horn-like protrusions present in only in males. They are among the largest group of beetle with many species reaching up to 6 inches in length. Despite their large and somewhat intimidating appearance, rhinoceros beetles are completely harmless as they can neither bite nor sting. 

The body of a rhinoceros beetle is covered in a hard exoskeleton made out of chitin. Their exoskeletons come in a variety of colorsthat differ from species to species, including red, black, purple, yellow. Most species have a pair of wings under their shell, though they have a hard time flying well due to their large size. Rhinoceros beetles are very strong and have been reported to lift up to 850 times their own body weight.  

Hercules beetle
The Hercules beetle (Dynastes hercules), one of the most well known rhinoceros beetles. Credit: WikiCommons

The obvious feature of rhinoceros beetles is their long horn-like appendages. Usually found only on the males of the different species, most rhinoceros beetle have two horns, one stemming upward from the front of the head and another horn placed at the rear of the thorax that points forward. Males use these horns for digging and to compete with other males during mating seasons. 

Rhinoceros beetles are strictly herbivorous. They subsist primarily on a diet of fruit, nectar and tree sap. Beetle larvae eat decaying vegetation. They are mostly nocturnal and spend their time during the day hiding under logs or leaves to camouflage themselves. Aside from their horns, they have relatively little defenses, so mostly rely on their size and appearance to deter potential predators. 

Common Rhino Beetle
A black male rhinoceros beetle. Credit: WikiCommons

During mating season, males will compete with other males for female attention, usually in the form of locking horns. After mating, the female will lay her eggs in a dark enclosed space near dead plant material. Females typically lay about 50 eggs on average. Once the eggs hatch, beetle larvae feed on rotted wood and leaves. Unlike adults who rarely consume much, rhinoceros beetle larvae have a significant appetite and will eat a lot of decaying wood. It can sometimes take up to 5 years for larvae to develop into adults. 

Rhinoceros beetles are popular pets as they are easy to maintain and safe to handle. In fact, in many parts of the world, people regularly consume rhinoceros beetles as food. It has been suggested that rhinoceros beetle larvae have more protein per unit of biomass than chicken or beef and could be a cheap and readily available supplement for diets deficient in protein. 

Interesting Facts about Rhinoceros Beetles

  • There are over 300 known species of rhinoceros beetle in the world. 
  • Rhinoceros beetles include the largest known species of beetle in the world, the Hercules beetle, which can grow up to 7 inches. 
  • In Asia, rhinoceros beetle fighting is a common pastime. Males will be pit against each other and spectators will place bets on the winner.
  • When threatened, they produce a loud hissing sound by rubbing their abdomen against their wing covers.