Occasionally, someone will bring in a large curious-looking insect for me to identify. Males have a big horn-like structure on their heads. Females have no horns.
These insects are in the group called scarab beetles. Their major colors are greenish to gray to nearly black, and they can be over two inches long.
These curious creatures are rhinoceros beetles and they are completely harmless. Sometimes people call them Hercules beetles, unicorn or horn beetles. There is a related insect called the triceratops beetle that is often mistaken for the rhinoceros beetle. Some folks even keep them for pets.
When kept as pets they are easy to care for. An aquarium with a generous layer of organic soil and a few pieces of rotting wood is good. Rhinoceros beetles are great burrowers. They don’t eat much and don’t require much water.
These critters aren’t exactly lovable, but they adapt to being handled and don’t bite. The only problem that can occur is that male beetles will often fight with each other. Some folks are fascinated by this and enjoy the fights.
Like all beetles, these guys go through four stages of development. In nature, females lay up to 50 eggs in decomposing plant material and these eggs hatch in three to four weeks.
These hatchlings are called larva or grubs and they undergo several molts to increase in size until they are ready to undergo the big change. During the larval stage, these critters eat rotting plant material. They don’t eat plant roots like many soil grubs do. Usually, the whole larva stage lasts about two and a half months.
The third stage is called the pupa stage and it is a resting period that usually takes about three weeks. Larvae burrow into the soil and create a pocket for the pupa to rest while it develops into an adult beetle. Pupas consume no food.
Adults generally live about three months and eat fruit, nectar and plant sap. Despite their large size, these beetles are still able to fly and are often seen flying toward a light source.
When flying beetles land, they can grasp objects quite efficiently with claws on their legs. Some people are intimidated by this, as beetles can be difficult to remove from clothing initially. Also, since they are large, they will land with a significant thud. This often scares folks.
Generally, these insects are nocturnal. In some places in Asia, they’re eaten as human food. In nature, snakes and birds are their major predators.
Rhinoceros beetles make hissing sounds when they’re disturbed. This noise is caused by their rubbing their wing covers against their abdomens. The noise is made strictly for show.
Rhinoceros beetles are one of the strongest creatures for their weight in the world. They can lift roughly 850 times their own weight. Only African dung beetles have a stronger relative size to strength ratio. I think this might be one reason people like them as pets. They can lift and move large objects in their environment.
Take notice the next time you see one of these beetles. You can even see one in the new Lion King movie. They’re really cool.
Ted Manzer teaches agriculture at Northeastern High School.