Editing Beetle (section)

====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/>