This week I have been busy preparing for the Guelph Bug Day, an event held at the University of Guelph. It’s full of insect and arachnid related activities, and I am fortunate enough to have a booth there to display my art. Of course, this means I have been drawing insects pretty much non-stop so I have lots of fun things to display. So we’ll be talking about rhinoceros beetles, because I drew one as part of my sticker collection for Bug Day.
I was under the impression that there were a handful of species of rhinoceros beetle, but I was quite mistaken. In fact, there are over three hundred species classified in the subfamily Dynastinae. They are found all over the world, in a range of habitats. Rhinoceros beetles are most common in tropical areas, and don’t like the cold — one of the only places they aren’t found is in polar regions. They are nocturnal, spending their days hiding in vegetation or under logs to protect themselves from predators.
Rhinoceros beetles are well-known for their large size, and the longest beetle species in the world is member of the Dynastinae. Male hercules beetles can reach a whopping 17.5 cm in length, including their immense horns (you can read more specifically about hercules beetles here). Rhinoceros beetles are quite heavily armoured, having a thick exoskeleton which can come in a variety of colours. They have two sets of wings, and can fly, though usually not very well as they are so large.
Another striking feature of rhinoceros beetles is their giant horns, which is where they get their name from. Only the males have horns, and in some species they can be ridiculously large and elaborate. The size, shape and number of these horns is variable, depending on the species. As well, the horns are a good indication of the nutritional status of the beetle — if the beetle is sick or not eating well, they will have smaller horns.
This is important, because male rhinoceros beetles use their horns for a very specific purpose: to fight for the right to breed. Thus the bigger their horns, the better chance the beetle will have of reproducing, and since males with bigger horns are generally healthier, theoretically the best genes are being passed along with each generation. Females lay about 50 eggs after mating, and rhinoceros beetles can spend several years as larvae before developing into pupae and then adults.
Though rhinoceros beetles are large (and often terrifying thanks to their giant horns), they aren’t dangerous to humans at all. They do not bite or sting, and adult beetles subsist on a friendly diet of nectar, sap and fruit. Larvae are the most voracious life stage, and they are known for eating much more than adult rhinoceros beetles. These guys don’t eat fruit, instead preferring to munch on rotting wood, which can make rhinoceros beetle larvae pests in some tree plantations.
Not everyone thinks rhinoceros beetles are pests — they are actually quite common as pets, as they are clean, low maintenance, and safe. Other people use the larvae as a food source, because they are very high in protein. The beetles are also studied for their aerodynamics, and may heavily influence future aircraft design. And finally, some people just like to watch these beetles fight. Two male beetles are put in an area in the presence of a female, and bets are placed on which male will emerge victorious. Rhinoceros beetles are such versatile creatures, aren’t they?
Cover image by George Chernilevsky, Public domain, via Wikimedia Commons