Major body parts of male and female stag beetles.
If you want to know more about the names shown in the body map, go to the glossary below.
Abdomen The hindmost of the three main body divisions of an insect: head, thorax and abdomen.
Aedeagus The part of the male sexual organs which is inserted into the female during mating and which carries the sperm. You can see it here.
Antenna (plural antennae) The sensory organs on the head. Stag beetles have two antennae or 'feelers' with a characteristic shape at the end, which is the same for all the beetles that belong to the Lucanidae family.
It is with their antennae that stag beetles pick up important pheromone signals.
Chitin The tough horny material, it is a nitrogenous polysaccharide, which forms the exoskeleton of an insect.
Cocoon A case which protects the pupa. The cocoon is constructed by the larva before it pupates. The greater stag beetle (Lucanus cervus) makes it out of compacted soil and about the size of a hen's egg. However lesser stag beetles Dorcus parallelipipedus just make a nice pupal chamber in the wood where they have been feeding.
Corpus luteum (plural corpora lutea) Means yellow body in Latin. During ovulation, that is when a mature egg leaves the ovariole, it breaks free of the membranes enveloping it and leaves them behind. These remains have a yellow coulour due to the presence of special compounds which, amazingly, are shared even with mammals. Their presence is an indirect indicator of the female's reproductive history.
Coxa (plural coxae) The first segment of the insect leg, often firmly attached to the body. Also known as the hip.
Crepuscular Times in the morning and evening when it is between daylight and dark. Crepuscular times are when some animal species are most active. Stag beetles, most moths and bats are often seen in the evening.
Dorsal surface Surface on the back of the body.
Egg bursters These structures are often hard to discover due to their small size, their name implies an important role in egg-hatching. They have been mentioned in Emdem, F. I. Van (1941): Larvae of British Beetles. II. A key to the British Lamellicornia larvae - Ent. Mon. Mag. 77:117-127, 181-19, with the following information: The first larval stage can be recognised by a pair of egg-bursters on the dorsolateral anterior part of the main-fold of the meso- and metanotum (Lucanidae, Geotrupidae) or only the latter (remaining Scarabaeidae, Passalidae).
Their photo would be very much appreciated for the website!
Eclosion The emergence of an adult insect from a pupal case or an insect larva from an egg. Have a look at a stag beetle ready to eclose here.
Elytron (plural elytra) The hard and horny wing case of a beetle. In stag beetles Lucanus cervus they have a lovely chestnut colour.
Exoskeleton The rigid external covering for the body of stag beetles, providing both support and protection.
External rumen It is a specific type of digestion whereby the faeces are further digested externally by micro-organisms, it was first described by Swift, M.J., Heal, O.W. and Anderson, M.J. (1979) in Decomposition in Terrestrial
Ecosystems. Blackwell Scientific, Oxford, UK.
The authors show in a diagrammatic way on page 92 how the cellulose is digested by animals. First, internally in the internal rumen, where the cellulases (enzymes that breakdown cellulose) are produced mainly either by symbionts in a modified region of the gut or by ingested micro flora during passage through unspecialised gut. Second, externally in the external rumen, by cellulases of soil and litter micro fora acting on the faeces. The latter allows for better assimilation of cellulose.
Exuvia The cast-off outer coat of an insect after a moult. When a mature stag beetle larva moults its skin splits along the back along with the cranial plates of the hard head capsule; this seems to allow the pupa to wriggle itself out of it completely. You can see it by the pupa here.
Fungus (plural fungi) Any of a group of organisms feeding on organic matter, including moulds, yeasts, mushrooms and toadstools.
Femur (plural femurs or femora) T he third, and often the largest segment of the insect leg.
Frass Debris or excrement produced by wood eating insects. Origin mid 19th cent.: from German Frass, from fressen 'devour'. Click here to view a typical example of a stag beetle larva surrounded by what it looks like shredded wood. Perhaps this habit gave rise to the German name Schröter.
Galea (plural galeae) Is part of the maxilla. In stag beetles, they are the paired feathery bits with which they mop-up the liquids.
Genus (plural genera) A group of closely related species. The name of the genus is incorporated into scientific names of all the member species. The scientific name of stag beetles is Lucanus cervus. Lucanus is the genus and cervus is the species.
Grey squirrel (Sciurus carolinenses) A north-American species introduced to Britain and Ireland and now the dominant squirrel in England and Wales. It is common in urban parks and suburban gardens wherever there are suitable trees.
In Britain the range of the Red squirrel (Sciurus vulgaris) has progressively declined during the last century as the Grey squirrel has spread, and the Red is now absent from most of England.
Guiro A musical instrument with a serrated surface which gives a rasping sound when scraped with a stick, originally made from an elongated gourd and used in Latin American music.
Head capsule width (HCW) The maximum width of the head in full view. The HCW can be an indicator of the instar of a particular larva. For a view on how this can be done, click here. According to Dyar's Law the linear dimensions of a larva's head increase linearly at each moult with rates constant for a given species.
Imago (plural imagos or imagines) The adult stage in the insect life history. Stag beetle Imagos come in all sizes, but unlike us they don't grow any more.
Instar The stage in an insect's life history between two moults. When a stag beetle larva first comes out of the egg it is in its first instar (L1). This tiny freshly hatched larva has a rigid head so, in order to grow, it has to shed its skin by moulting. This way the second instar (L2) is the larva after the first moult; the third instar (L3) is the larva after the second moult.
In general, Lucanus cervus stag beetle larvae reach their third instar around the end of their first year, and after that will spend at least another year fattening up before they are ready to pupate.
Invertebrate Any animal lacking a backbone, such as insects, wood lice, centipedes, spiders, etc.; also worms and snails.
Labium (plural labia) The lower lip of the insect mouthparts. In stag beetles it has a sensory palp with which they taste their food and a specialised part covered with bristles, it is called the ligula. For a dissected view of the labium click here.
Labrum The upper lip of the insect mouthparts: a small hardened body part on the front of the head. In stag beetles it is clearly seen between the mandibles. Its shape can be a good identification clue as it varies quite a bit with the species, and the gender as well.
Larva (plural larvae) Name given to an young insect when it is markedly different from the adult. The larvae must pass through a pupal stage before becoming adults.
Magpie (Pica pica) Common black-and-white long-tailed bird of the crow family. Unfortunately some members of this family, Corvidae, like eating beetles, in particular stag beetles. Click here for more.
Mandible The biting moutparts of an insect. In male stag beetles they are very large and look like antlers, hence the name "stag beetle"; they are used for combat/defence and have become useless for eating.
However stag beetle larvae have very sharp mandibles and they use them to feed on sometimes quite hard wood.
Maxilla (plural maxillae) The jaw of an insect. In stag beetles they have a sensory palp with which they taste their food, plus the galea which is adapted for sucking. For a dissected view of the maxilla click here.
Metamorphosis (plural metamorphoses) Name given to the changes that take place during the insect's life as it turns from an immature form to an adult.
The stag beetle's larva changes to an adult beetle during the pupal stage, that is it undergoes a complete reorganization in order to become a shiny beetle.
Moult To moult is to shed the outer cover of the body. The stag beetle's larva has a hard shiny head which unlike its body is not elastic at all. So in order to grow it has to shed its outer cover. After each moult it gets bigger and fatter. By the time that it has reached the last instar its head is several times the size it was when it first came out of the egg and its body is the size of a person's thumb.
Mycangium (plural mycangia) A microbe-storage organ found in some invertebrates who develop in wood. The mycangium in stag beetles took very long to be discovered because it is hidden in a fold of the female's exoskeleton. The males do not have a mycangium. It was first described by Japanese researchers *. It is a hidden organ associated with the ovipositor which will evert during the life of a female in very private circumstances. For the first time soon after eclosion deep in the soil inside a cocoon. This is when the female gathers with the mycagiunm the microbes left on the cocoon wall by the larva when it emptied its gut, just before pupation. Afterwards, it everts every time that the female lays an egg; this in order to swab the area around the egg with the mycancium symbionts; this also happens deep in the soil. Sometimes when a female is accidentally trodden on the mycagium becomes visible.
* Tanahashi M., Kubota K., Matsushita N. and Togashi K., 2010. Discovery of mycangia and associated xylose-fermenting yeasts in stag beetles (Coleoptera: Lucanidae). Naturwissenschaften 97: 311-317).
Hawes, C.J. & Tanahashi, M., 2016. A brief review of mycangia and associated yeast symbionts in British stag beetles. Bulletin de la Société royale belge d’Entomologie, 152 (2): 174-176.
Ovariole (plural ovarioles) Tube where the eggs (ova) develop. The number of ovarioles may vary from species to species, but both Lucanus cervus and Dorcus parallelipipedus have 12 per ovary.
Ovary (plural ovaries) The female reproductive organ that produces eggs (ova). Each ovary has a number of ovarioles which contain the developing eggs (ova). The beetles which belong to the Superfamily Scarabaeoideae have two ovaries; except, the dung beetles of the Subfamily Scarabaeinae, which the majority have just one ovary consisting of a single ovariole.
Ovipositor The egg-laying apparatus of a female insect, it is used to place the fertilized eggs in the appropriate position. In the female stag beetle is concealed but, like the mycangium, it will protrude when she lays her eggs or when she is accidentally trodden on.
Pabulum (plural pabula) Any substance that can be used as food.
Palps Short feelers coming from the mouth. There are two pairs of palps in stag beetles; they are mostly for tasting food.
Parthenogenic Refers to asexual reproduction. This doesn't occur with stag beetles, of course, but it happens with quite a number of insects, during some stage of their life cycle; for instance, with the apple gall wasp during their root gall stage.
Pars stridens The stridulating part. In stag beetle larva this is a series of ridges on the coxa of the middle legs. In the musical instrument guiro it is a serrated surface on a gourd.
Pheromone A chemical substance produced and released into the environment by an animal, especially a mammal or an insect, affecting the behaviour or physiology of others of its species.
Plectrum Something with which to strike. In stag beetle larvae it is composed of a series of ribs on the trochanter. In the musical instruments guiro or reco-reco it is a stick.
Predator An animal that usually preys on others: magpies in some areas are the major predators of stag beetles.
Pre-pupa A resting stage through which many larvae pass before turning into pupae. The larvae are usually rather shrunken and deformed during this stage.
Proboscis Name given to various kinds of sucking mouths in which some of the mouth-parts are drawn out to form a long tube, like in some butterflies.
Stag beetles have feathery tubes that they can extend to suck their food with.
Pronotum The back surface of the first part of the thorax. In a stag beetle, looking from above, it is the body part between the head and the wing cases.
Pupa (plural pupae) The third stage in the life cycle of a stag beetle while it undergoes a complete metamorphosis. It is during the pupal stage, which does not feed and does not move about, that the larval body of a stag beetle is rebuilt into that of an adult insect. Derivatives: pupal (adjective).
Pupate To pupate is to turn into a pupa; go through the pupal stage. Related forms: pupation (noun).
Pyramid A special construction of aged hard wood logs to attract stag beetles and other saproxylic invertebrates. E. Tochtermann, its inventor, called it Hirschkäferwiege, meaning stag beetle cradle.
Reco-reco A Brazilian percussion instrument of Angolan origin, consisting of a length of bamboo with transverse notches cut into it and over which a wand is rubbed to produce a rasping intermittent sound.
Saprophyte A plant, a fungus, or micro-organism that lives on dead or decaying organic matter.
Saproxylic Pertaining to dead or decaying wood.
Saproxylic beetles Beetles which are involved in or dependent on the process of fungal decay of wood, or on the products of that decay, and which are
associated with living as well as dead trees *. Stag beetles (Lucanus cervus), lesser stag beetles (Dorcus parallelipipedus) and all the other Lucanidae species are dependent on the process of fungal decay of wood during their larval stage.
Alexander, K.N.A. - Tree biology and saproxylic Coleoptera: issues of definitions and conservation language: 9-13. In Vignon V., Asmodé J.-F. (eds). Proceedings of the 4th Symposium on the Conservation and Workshop of Saproxylic Beetles, Vivoin (72) / France, 27th-29th June, 2006. Rev. Écol. (Terre Vie), suppt. 10.
Scutellum The part of the middle segment of the thorax, which you can see from above. In stag beetles it is the triangular bit at the top of the wing cases.
Species The basic unit of living things, consisting of a group of individuals which all look more or less alike and which can all breed with each other to produce another generation of similar creatures. Many species are subdivided into sub-species. These normally inhabit different areas and they may differ in appearance, but they can still all interbreed.
Spiracles Openings on the thorax and abdomen of insects that allow the insect to breathe. They are particularly visible on body of light coloured beetle's larvae as they are rather dark. In the larvae of the stag beetles they are C shaped and all face the same way, whereas in the chafers' larvae they are round and very dark, a good identification clue. For more visit Gardener's Larva Guide.
Stridulation The production of sounds by rubbing two parts of the body together; best known in crickets, grasshoppers and cicadas. But some beetles also stidulate. For instance, the larvae of the Lucanidae, Passalidae and some of the Geotrupidae stridulate by rubbing their legs together. They rub a series of ridges on the coxa of the middle legs with the plectrum on the trochanter of the hind legs. See this video of a stridulating Lucanus cervus larva. The Cetoniinae larvae stridulate by rubbing their mouthparts together, which is called a maxillo-mandibular stridulating apparatus. See this video of a stridulating Cetonia aurata larva.
Sub-species See Species.
Synanthropic Literally "living with man". Some old German vernacular names for Lucanus cervus attest to that; see Feuershröter. Even though stag beetles are strongly associated with urban gardens some entomologists do not consider them as a synanthropic species on the basis that they can also live elsewhere. According to Paul Whitehead the term synanthropic is now referred to as culture favoured.
Tarsus The 'foot' of the insect: primitively a single segment but now usually divided up into several sub-segments.
Teneral Condition of recently moulted individuals, when they are pale and soft-bodied. For an example of a freshly emerged stag beetle click here. Origin: Latin Tener, -eris, tender, delicate.
Thorax The middle of the three major divisions of the insect body. The wings and the legs always come from the thorax. The thorax is itself divided into three segments, one for each pair of legs. In stag beetles the first segment is called the pronotum and is easily seen from above. The other two segments are hidden by the wing cases, except for a triangular bit of the middle segment, the scutellum. Seen from below each thoracic segment has a pair of legs attached to it.
Tibia One of the segments of the leg, between femur and tarsus.
Trochanter A segment of the insect leg between the coxa and the femur, often very small and easily overlooked. However the trochanter in the hind legs of stag beetle larvae is very well developed.
White-rot A type of wood decay in which the cellulose, hemicellulose, and lignin components of the wood are decomposed, leaving the wood soft, white, and fibrous. Some saproxylic species can develop only on white-rot, others like Lucanus cervus are generalists, that is, they will breed in a wide range of wood so long it has a suitable state of decay.
Wood mould Fine soft loose wood which has been decomposed by fungi together with other micro-organisms. In it there are often found insect body remains, their faecal pellets, etc.
Acknowledgement - I must confess that the source of some of the above terms was Michael Chinery's A Field Guide to the Insects of Britain and Northern Europe, 1977.
Entomologists' glossary - The Amateur Entomologists' Society has a superbly illustrated glossary with well over 360 terms. This is the ongoing work of Dr. Kieren Pitts.
Last modified: Sat April 28 2018
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