subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
(Scarabaeidae). Other common names – some for particular groups of rhinoceros beetles – include
Hercules beetle
The Hercules beetle (''Dynastes hercules'') is a species of Dynastinae, rhinoceros beetle native to the rainforests of southern Mexico, Central America, South America, and the Lesser Antilles. It is the List of largest insects#Beetles (Coleopter ...
s, unicorn beetles or horn beetles. Over 1,500
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
and 225
genera
Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...
of rhinoceros beetles are known.
Many rhinoceros beetles are well known for their unique shapes and large sizes. Some famous species are, for example, the Atlas beetle (''Chalcosoma atlas''), common rhinoceros beetle (''Xylotrupes ulysses''), elephant beetle (''Megasoma elephas''), European rhinoceros beetle (''Oryctes nasicornis''),
Hercules beetle
The Hercules beetle (''Dynastes hercules'') is a species of Dynastinae, rhinoceros beetle native to the rainforests of southern Mexico, Central America, South America, and the Lesser Antilles. It is the List of largest insects#Beetles (Coleopter ...
The Dynastinae are among the largest of beetles, reaching more than in length, but are completely harmless to humans because they cannot bite or sting. Some species have been anecdotally claimed to lift up to 850 times their own weight. An extinct
Eocene
The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
exoskeleton
An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...
. A pair of thick wings lie atop another set of membranous wings underneath, allowing the rhinoceros beetle to fly, although not very efficiently owing to its large size. Their best protection from predators is their size and stature, also avoiding many due to being
nocturnal
Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite.
Nocturnal creatur ...
. When the sun is out, they hide under logs or in vegetation to
camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
themselves from the few predators big enough to eat them. If rhinoceros beetles are disturbed, some can release very loud, hissing squeaks created by rubbing their abdomens against the ends of their wing covers.
Ecology
These beetles'
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
l stages can be several years long. The larvae feed on rotten wood and the adults feed on
nectar
Nectar is a viscous, sugar-rich liquid produced by Plant, plants in glands called nectaries, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to an ...
,
plant sap
Sap is a fluid transported in the xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant.
Sap is distinct from latex, resin, or cell sap; it is a sep ...
, and
fruit
In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering.
Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
. First, the larvae hatch from eggs and later develop into pupae before they reach
adult
An adult is an animal that has reached full growth. The biological definition of the word means an animal reaching sexual maturity and thus capable of reproduction. In the human context, the term ''adult'' has meanings associated with social an ...
hood.
Mating
Male Japanese rhinoceros beetles (''Allomyrina dichotoma'') fight to dominate sap sites. Males use their horns to pry rival males off the area, which also may give them the chance to mate with a female. In this and other species that defend mating sites, larger males with larger horns mate more frequently, as they win more contests. Small males often avoid larger males and exhibit alternative strategies to gain access to females.
As pests
Some species, such as the coconut rhinoceros beetle ('' Oryctes rhinoceros''), can become major pests, e.g., in tree plantations. Usually though, beetle population densities are not as high as in some other pest insects, and they typically prefer food trees which are already sick or dying from some other cause. Some species' larvae, however, will attack healthy trees or even
root vegetable
Root vegetables are underground plant parts eaten by humans or animals as food. In agricultural and culinary terminology, the term applies to true roots, such as taproots and root tubers, as well as non-roots such as bulbs, corms, rhizomes, and ...
s, and when they occur in large numbers, can cause economically significant damage. The fungus '' Metarhizium majus'' is a proven biocontrol agent for beetle infestation in crops.
Uses
Rhinoceros beetles have become popular pets in parts of
Asia
Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...
, due to being relatively clean, easy to maintain, and safe to handle. Also in Asia, male beetles are used for gambling fights. Since males naturally have the tendency to fight each other for the attention of females, they are the ones used for battle. To get the two male beetles to lock in combat, a female beetle is used, or a small noisemaker duplicating the female's
mating call
A mating call is the auditory signal used by animals to attract mates. It can occur in males or females, but literature is abundantly favored toward researching mating calls in females. In addition, mating calls are often the subject of mate choi ...
.
Entomologist Séverin Tchibozo suggests the larvae contain much more
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
(40%) than
chicken
The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...
(20%) and
beef
Beef is the culinary name for meat from cattle (''Bos taurus''). Beef can be prepared in various ways; Cut of beef, cuts are often used for steak, which can be cooked to varying degrees of doneness, while trimmings are often Ground beef, grou ...
National Science Foundation
The U.S. National Science Foundation (NSF) is an Independent agencies of the United States government#Examples of independent agencies, independent agency of the Federal government of the United States, United States federal government that su ...
-funded research, examined the function and aerodynamics of '' Allomyrina dichotoma'' with the help of researchers in
Drexel University
Drexel University is a private university, private research university with its main campus in Philadelphia, Pennsylvania, United States. Drexel's undergraduate school was founded in 1891 by Anthony Joseph Drexel, Anthony J. Drexel, a financier ...
's Mechanical Engineering Department and in collaboration with Konkuk University in South Korea. Rhinoceros beetles could play a big part in the next generation of aircraft design.
Cyclocephala
''Cyclocephala'' is a genus of scarab beetles from the subfamily Dynastinae (Coleoptera, Scarabaeidae). Beetles of this genus occur from southeastern Canada to Argentina, India and the West Indies.
Adults of this genus are nocturnal or crepuscu ...
Enema
An enema, also known as a clyster, is the rectal administration of a fluid by injection into the Large intestine, lower bowel via the anus.Cullingworth, ''A Manual of Nursing, Medical and Surgical'':155 The word ''enema'' can also refer to the ...