Editing Beetle (section)

==Reproduction and development==
Beetles are members of the [[Order (biology)|superorder]] [[Holometabola]], and accordingly most of them undergo complete [[metamorphosis]]. The typical form of metamorphosis in beetles passes through four main stages: the [[egg]], the [[larva]], the [[pupa]], and the [[imago]] or adult.<ref name="Winkler">{{cite book |last=Winkler|first=Josef Rudolf |title=A Book of Beetles|url=https://books.google.com/books?id=xP5CAAAAYAAJ|year=1964|publisher=[[Spring Books]] Science |isbn=|pages=30–32}}</ref> The larvae are commonly called [[Larva|grubs]] and the pupa sometimes is called the chrysalis. In some species, the pupa may be enclosed in a cocoon constructed by the larva towards the end of its final [[instar]]. Some beetles, such as typical members of the families [[Meloidae]] and [[Rhipiphoridae]], go further, undergoing [[hypermetamorphosis]] in which the first instar takes the form of a [[triungulin]].<ref>{{cite journal |url=https://www.researchgate.net/publication/242221698 |author1=Ozbek, H. |author2=Szalokia, D. |date=1998 |title=A contribution to the knowledge of the Meloidae (Coleoptera) fauna of Turkey along with new record |journal=Turkish Journal of Zoology |volume=22 |pages=23–40}}</ref>

===Mating===
[[File:Punctate Flower Chafer.jpg|thumb|[[Punctate flower chafer]]s (''Neorrhina punctata'', Scarabaeidae) mating]]

Some beetles have intricate mating behaviour. [[Pheromone]] communication is often important in locating a mate.
Different species use different pheromones. [[White worm beetle|Scarab beetles]] such as the [[Rutelinae]] use pheromones derived from [[fatty acid synthesis]] and others use pheromones from organic compounds, while other scarabs such as the [[Melolonthinae]] use [[amino acid]]s and terpenoids. Another way beetles find mates is seen in the [[fireflies]] (Lampyridae) which are [[bioluminescent]], with abdominal light-producing organs. The males and females engage in a complex dialog before mating; each species has a unique combination of flight patterns, duration, composition, and intensity of the light produced.<ref name=insenc/>

Before mating, males and females may stridulate, or vibrate the objects they are on. In the Meloidae, the male climbs onto the dorsum of the female and strokes his antennae on her head, palps, and antennae. In ''[[Eupompha]]'', the male draws his antennae along his longitudinal vertex. They may not mate at all if they do not perform the precopulatory ritual.<ref name=insenc/> This mating behavior may be different amongst dispersed populations of the same species. For example, the mating of a [[Russia]]n population of [[tansy beetle]] (''Chrysolina graminis'') is preceded by an elaborate ritual involving the male tapping the female's eyes, pronotum and antennae with its antennae, which is not evident in the population of this species in the [[United Kingdom]].<ref>{{cite journal |author1=Medvedev, L. N. |author2=Pavlov, S. I. |date=1988 |title=Mating behavior of the Chrysomelidae (Coleoptera) |journal=Entomological Review |volume=67 |pages=100–108}}</ref>

In another example, the [[intromittent organ]] of male [[thistle tortoise beetle]]s is a long, tube-like structure called the [[flagellum]] which is thin and curved. When not in use, the flagellum is stored inside the [[abdomen]] of the male and can extend out to be longer than the male when needed. During mating, this organ bends to the complex shape of the female [[reproductive organ]], which includes a coiled duct that the male must penetrate with the organ. Furthermore, these physical properties of the thistle tortioise beetle have been studied because the ability of a thin, flexible structure to harden without buckling or rupturing is mechanically challenging and may have important implications for the development of microscopic [[catheter]]s in modern medicine.<ref>{{Cite journal |last1=Matsumura |first1=Yoko |last2=Kovalev |first2=Alexander E. |last3=Gorb |first3=Stanislav N. |date=December 2017 |title=Penetration mechanics of a beetle intromittent organ with bending stiffness gradient and a soft tip |journal=Science Advances |volume=3 |issue=12 |pages=eaao5469 |doi=10.1126/sciadv.aao5469 |issn=2375-2548 |pmc=5738233 |pmid=29279866}}</ref>

[[Competition (biology)|Competition]] can play a part in the mating rituals of species such as [[burying beetle]]s (''Nicrophorus''), the insects fighting to determine which can mate. Many male beetles are [[Territory (animal)|territorial]] and fiercely defend their territories from intruding males. In such species, the male often has horns on the head or thorax, making its body length greater than that of a female. Copulation is generally quick, but in some cases lasts for several hours. During copulation, [[Spermatozoon|sperm cell]]s are transferred to the female to [[fertilize]] the egg.<ref name="Gilliott"/>

===Life cycle===
[[File:Life cycle of stag beetle.svg|thumb|300px|The life cycle of the [[stag beetle]] includes three [[instar]]s.]]

====Egg====
Essentially all beetles lay eggs, though some [[myrmecophilous]] [[Aleocharinae]] and some [[Chrysomelinae]] which live in mountains or the subarctic are [[ovoviviparous]], laying eggs which hatch almost immediately.<ref name="Winkler" /> Beetle eggs generally have smooth surfaces and are soft, though the [[Cupedidae]] have hard eggs. Eggs vary widely between species: the eggs tend to be small in species with many instars (larval stages), and in those that lay large numbers of eggs.
A female may lay from several dozen to several thousand eggs during her lifetime, depending on the extent of parental care. This ranges from the simple laying of eggs under a leaf, to the parental care provided by [[scarab beetles]], which house, feed and protect their young. The [[Attelabidae]] roll leaves and lay their eggs inside the roll for protection.<ref name=insenc/><ref name=Crowson>{{cite book |last=Crowson |first=R. A. |title=The Biology of the Coleoptera |url=https://books.google.com/books?id=WMXYBAAAQBAJ&pg=PA360 |year=2013 |publisher=[[Elsevier]] Science |isbn=978-1-4832-1760-4 |pages=358–370}}</ref>

====Larva====
The [[larva]] is usually the principal feeding stage of the beetle [[Biological life cycle|life cycle]]. Larvae tend to feed voraciously once they emerge from their eggs. Some feed externally on plants, such as those of certain leaf beetles, while others feed within their food sources. Examples of internal feeders are most [[Buprestidae]] and longhorn beetles. The larvae of many beetle families are predatory like the adults (ground beetles, ladybirds, rove beetles). The larval period varies between species, but can be as long as several years. The larvae of [[skin beetle]]s undergo a degree of reversed development when starved, and later grow back to the previously attained level of maturity. The cycle can be repeated many times (see [[Biological immortality]]).<ref>{{cite journal |last1=Beck |first1=S. D. |last2=Bharadwaj |first2=R. K. |year=1972 |title=Reversed development and cellular ageing in an insect |journal=[[Science (journal)|Science]] |volume=178 |pages=1210–1211 |bibcode=1972Sci...178.1210B |doi=10.1126/science.178.4066.1210 |pmid=4637808 |issue=4066|s2cid=34101370 }}</ref> Larval morphology is highly varied amongst species, with well-developed and sclerotized heads, distinguishable thoracic and abdominal segments (usually the tenth, though sometimes the eighth or ninth).<ref name="Gilliott"/>

[[File:Hercules beetle (larva).jpg|thumb|left|upright=0.6|[[Scarabaeoidea|Scarabaeiform]] larva of [[Hercules beetle]]]]

Beetle larvae can be differentiated from other insect larvae by their hardened, often darkened heads, the presence of chewing mouthparts, and [[Spiracle (arthropods)|spiracle]]s along the sides of their bodies. Like adult beetles, the larvae are varied in appearance, particularly between beetle families. Beetles with somewhat flattened, highly mobile larvae include the ground beetles and rove beetles; their larvae are described as campodeiform. Some beetle larvae resemble hardened worms with dark head capsules and minute legs. These are elateriform larvae, and are found in the [[click beetle]] (Elateridae) and [[darkling beetle]] (Tenebrionidae) families. Some elateriform larvae of click beetles are known as wireworms. Beetles in the [[Scarabaeoidea]] have short, thick larvae described as scarabaeiform, more commonly known as grubs.<ref>{{cite web |url=https://www.amentsoc.org/insects/glossary/terms/scarabaeiform |title=Definition of 'Scarabaeiform' |publisher=[[Amateur Entomologists' Society]] |access-date=2017-01-27}}</ref>

All beetle larvae go through several [[instar]]s, which are the developmental stages between each [[ecdysis|moult]]. In many species, the larvae simply increase in size with each successive instar as more food is consumed. In some cases, however, more dramatic changes occur. Among certain beetle families or genera, particularly those that exhibit parasitic lifestyles, the first instar (the [[planidium]]) is highly mobile to search out a host, while the following instars are more sedentary and remain on or within their host. This is known as [[hypermetamorphosis]]; it occurs in the [[Meloidae]], [[Micromalthidae]], and [[Ripiphoridae]].<ref>{{cite book |author1=Krinsky, W. L. |editor1=Mullen, G. R. |editor2=Durden, L. A. |date=2009 |title=Medical and Veterinary Entomology |edition=2nd |chapter=8 Beetles (''Coleoptera'') |pages=101–115 |publisher=[[Elsevier]] |isbn=978-0-12-372500-4}}</ref> The blister beetle ''[[Epicauta vittata]]'' (Meloidae), for example, has three distinct larval stages. Its first stage, the [[triungulin]], has longer legs to go in search of the eggs of grasshoppers. After feeding for a week it moults to the second stage, called the caraboid stage, which resembles the larva of a [[Carabidae|carabid beetle]]. In another week it moults and assumes the appearance of a [[Scarabaeidae|scarabaeid larva]]—the scarabaeidoid stage. Its penultimate larval stage is the pseudo-pupa or the coarcate larva, which will overwinter and pupate until the next spring.<ref>{{cite web |url=http://bugguide.net/node/view/149686 |title=Hypermetamorphosis of Striped Blister Beetle – ''Epicauta vittata'' |date=2007 |publisher=BugGuide |access-date=2017-01-27}}</ref>

The larval period can vary widely. A fungus feeding staphylinid ''[[Phanerota fasciata]]'' undergoes three moults in 3.2 days at room temperature while ''Anisotoma'' sp. (Leiodidae) completes its larval stage in the fruiting body of slime mold in 2 days and possibly represents the fastest growing beetles. Dermestid beetles, ''Trogoderma inclusum'' can remain in an extended larval state under unfavourable conditions, even reducing their size between moults. A larva is reported to have survived for 3.5 years in an enclosed container.<ref name=insenc/>

====Pupa and adult====
[[File:Eburia quadrigeminata.jpg|thumb|The ivory-marked beetle, ''[[Eburia quadrigeminata]]'', may live up to 40 years inside the [[hardwood]]s on which the larva feeds.]]

As with all holometabolans, beetle larvae pupate, and from these [[pupa]]e emerge fully formed, sexually mature adult beetles, or [[imago]]s. Pupae never have mandibles (they are [[adecticous]]). In most pupae, the appendages are not attached to the body and are said to be [[exarate]]; in a few beetles (Staphylinidae, Ptiliidae etc.) the appendages are fused with the body (termed as [[Pupa#Position in life cycle|obtect]] pupae).<ref name="Gilliott"/>

Adults have extremely variable lifespans, from weeks to years, depending on the species.<ref name="Gilliott"/><ref name="ausbeetle"/> Some wood-boring beetles can have extremely long life-cycles. It is believed that when furniture or house timbers are infested by beetle larvae, the timber already contained the larvae when it was first sawn up. A [[birch]] bookcase 40 years old released adult ''[[Eburia quadrigeminata]]'' ([[Cerambycidae]]), while ''[[Buprestis aurulenta]]'' and other [[Buprestidae]] have been documented as emerging as much as 51 years after manufacture of wooden items.<ref name="Zeng">{{cite web|last1=Zeng|first1=Yong|title=Longest Life Cycle|url=http://entnemdept.ifas.ufl.edu/walker/ufbir/chapters/chapter_12.shtml|publisher=University of Florida|access-date=17 March 2017|date=1995}}</ref>