I can’t imagine why, but rhino beetles are sometimes kept as pets (cue mental image of taking one for a walk on a lead!), and there are numerous sites on the internet giving advice on their care. Despite their large and somewhat intimidating appearance, they are completely harmless to humans, their bite is not even a pinch, and they don’t sting. The body of a rhino beetle is covered in a hard exoskeleton made out of ‘chitin’, similar to keratin - which in humans makes hair and nails - but for beetles, it generates a hard outer shell or armour for protection.
These gargantuan nocturnal beetles, of which there are over 1,500 species, are known for their unique shapes and large sizes and are found on every continent except Antarctica. Leaf litter, plants, and fallen logs provide a safe hideout for them during the day. You will see the European Rhinoceros Beetle occasionally even here in Portugal, which comes in at a modest size of around 6cm long, and although this makes it one of the smaller species of rhinoceros beetle, it is still one of the largest and heaviest beetles found in Europe. When disturbed, rhino beetles can produce hissing squeaks. These aren’t actually vocal noises—instead, they’re produced when the beetle rubs its abdomen and wing covers together. The horns of the male rhino beetle are used to drive other males away from a female beetle during mating rituals. Females lay about 50 eggs, which hatch into larvae, and after several moults, they eventually reach adult size and form. Longevity varies among species, but a typical lifespan is one to two years, much of which may be spent in the larval stage.
Rhino beetles are herbivorous insects feeding on fruit, nectar and tree sap that they tap with their horns, and the larvae feed on decaying plant matter. Named for the horn-like projections on and around the males' heads, most are black, grey, or greenish in colour, and some are covered in soft hairs. Another name given to some of these insects is the Hercules beetle, because of their immense strength. Adults of some species can lift objects 850 times their weight (that would be like a human lifting twenty mid-sized cars). One way the beetles use this extreme strength is to dig themselves into leaf litter and soil to escape danger, and their horns help them to do this. Some species can grow up to 15 centimetres in length, making them some of the largest beetles in the world.
The heaviest beetles in the world are a group called Megasoma, found in South and Central America, with the Actaeon beetle being the heaviest, particularly at its larval stage, which can last up to three years. Sizewise, it would fill the palm of your hand!
Titan beetles and Hercules beetles are the two biggest species in the group known as Coleoptera. Considering body length alone, the titan beetle is the longest. These giant insects look a bit like a cockroach, but they are a species of longhorn beetle. These can reach a massive 16.7cm long and are found in some of South America's hottest tropical jungles. They have exceptionally strong jaws, sharp defensive spines and the ability to make a hissing squeak by expelling air through their ‘spiracles’ or breathing holes, along their sides. This noise shouldn’t alarm you unless you are another beetle of course! I watched a video of one of these morphing from a larva into a beetle, and to me, it was pretty gross, like watching an alien emerging.
Rhino beetle eggs, larvae, pupae, and adults may be attacked by various predators, including pigs, rats, ants, and some other beetles. They may also be killed by two important diseases: the fungus Metarhizium anisopliae and the Oryctes virus disease.
Rhino Beetles are much sought after as beetle pets, and for good reason – their size. But be warned – they naturally have a small number of mites on them. For this reason, many people keep the beetles outside. The mites and beetles live comfortably together, but the mites can act as intermediate hosts for unwanted tapeworm parasites in domestic animals.
Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man.