Clown beetle
Encyclopedia
Histeridae is a family
of beetle
s commonly known as Clown beetles or Hister beetles. This very diverse group of beetles contains 3,900 species
found worldwide. They can be easily identified by their shortened elytra that leaves two of the seven tergites exposed, and their elbowed antennae
with clubbed ends. These predatory feeders are most active at night and will fake death if they feel threatened. This family of beetles will occupy almost any kind of niche
throughout the world. Hister beetles have proved useful during forensic investigations to help in time of death estimation. Also, certain species
are used in the control of livestock pests that infest dung
and to control houseflies. Because they are predacious
and will even eat other Hister beetles, they must be isolated when collected.
The Hister beetles are easily identified by their shiny elytra which is typically shiny black or metallic green. The two main shapes for this family are oval and flat. The elytra is shorter than the thorax
with typically two of the seven tergites exposed. Hister beetles have specialized heads that can retract into their prothorax
and two elbowed antennae
with clubbed ends. As predatory feeders, the Hister beetles commonly feed on the Egg
, larval, and adult
stages of other insects. Certain species are also used to control livestock
pests that infest dung or to control house flies. Histeridae are most active at night and they will play dead if they feel threatened.
. Histeridae has two common names, the “Clown” beetle and the “Hister” beetle. There have been several theories explaining the origin of these common names. One theory for the “Hister” nickname comes from the work of Juvenal
, a Roman poet. Juvenal used the word “hister” to mean a dirty, lowly being. Another theory for the origin of this beetle's name stems from the fact that in Latin, “hister” means actor. Many people believe the name is associated with the Hister beetles’ ability to imitate death when they are disturbed. Still, some believe this family of beetles was named for its physical characteristics. The Clown beetle has flattened legs, which can be compared to a clown’s flat shoes or loose-fitting pants.
As with all insects, the body consists of a head, thorax, and abdomen. The thorax is divided into the prothorax, mesothorax
and metathorax
; the dorsal side of the prothorax is a sclerotized shield, the pronotum. The Hister beetle has an exoskeleton
made of chitin
which gives protection to the internal organs. The elytra and forewings are normally well developed in beetles, but in Histerdiae the elytra are shortened and rectangular. The shortened elytra expose the final two of the seven tergites. Attached to the body are three pairs of jointed legs and two pairs of wings. The head has compound eyes, a mandible mouthpart
, and shortened antennae
. The eyes do not move; each takes a little piece of the picture to make a complete picture. The Hister's mouthpart grasps and grinds the food with two teeth. Lastly, the antennae
work as sensory organs. A distinctive characteristic is that the antennae are elbowed and contain three antennomeres that form a club at the end.
Clown beetles have an open circulatory system
within its hemocoel, also known as a body cavity. They have a tube shaped heart that spans the length of the body, and use hemolymph
as blood. This blood does not contain any oxygen, but carries nutrients throughout the body. Spiracles are located on the abdomen and are the tracheal system of the beetle. Oxygen is brought into the body by spiracles and tiny sacks exchange the oxygen like a mammal's lung. The beetles digestive system is known as an alimentary canal. The digestive system feeds the circulatory system. Within the canal, food and water are broken down, absorbed and excreted.
, dead vegetation, sandy areas, under tree bark, mammal burrows, and ant/termite colonies. Charactertistics of the Hister beetle are dependent upon its habitat. For example, the flat Hister beetles are found under bark, while the cylindrical beetles are not. Shape of the beetle will vary from species to species.
A unique ability of the Hister beetle is their capacity to live in close proximity with ants (myrmecophiles) and termites (termitophiles). The Hister beetles can live in harmony with the ants or predate on the ants, depending on the species.
Histeridae’s habitat is wide spread because they feed on other arthropods. As new food sources are introduced into an environment, the predators of that food source will soon follow. Histeridae live in areas where their prey feed. Some examples are mammalian nests where other arthropods scavenge for food or carrion where maggots will arrive.
. When found on dung, carrion and vegetation, the Hister beetles will feed on the fly larvae found there. The predacious Hister beetle will feed on soft-bodied insect eggs and larvae, Diptera
in particular. Some species of Histeridae will even feed on other Histeridae.
The majority of Histeridae species prefer dried, decaying habitats. When found on carrion the adult Histeridae will usually be feeding on Diptera maggots, not the rotting material. The larvae of Hister beetles feed on the blowfly pupae found on the body.
Some Histeridae species live in an integrated nest with ants and termites. Some species have been found to be fed by the ants, while others simply feed on leftover insect larvae that the ants do not want. In contrast, in their adult stage Psiloscelis will actually feed on adult ants.
Because the Histeridae are predacious they can be utilized as control agents, but must be stored in isolation. The Hister beetles have proven useful in both the control of pest flies in poultry houses and pastures, and against pest beetles of stored food products.
. In this type of development the larval form does not resemble the adult form and the pupae has internally developing wing
s. They also undergo an immobile pupal stage where they do not eat. After the pupal stage they emerge in their adult form.
The Histeridae life cycle consists of egg
, larval, pupa
l and adult
stages of development:
to adult
at 30 degrees celsius is 20.5 days. The eggs of most species are off-white and oval in shape. The egg takes on average 3.8 days +/- 0.02 to develop into the first instar
. The chorion
is shiny and smooth. In certain species like epirerus or platylomalus it can look pale brown and be leathery in texture.
is the longest stage of its entire development, taking up 39% of the overall development time. It takes 5.1 days +/- 0.1 on average for the first instar
to develop into the second. The larval form of the insect will range in length from three millimeters to several centimeters. They have a membranous body with a limited amount of sclerotization around the head. There is some pigmentation around the body and it is horizontally segmented. The legs are short and do not help much in locomotion
. They move mostly through muscular contraction.
while the male's is adapted as a copulatory structure. The female has oviducts that carry the developed eggs from the ovaries to the ovipositor
. The males also have a duct that carries the sperm
from the testes to the copulatory structure, which stays concealed until copulation. When fertilization takes place, the male leaves enough sperm in the female to fertilize all the eggs in the female's ovaries. The excess sperm is kept in a special structure called spermatheca
which holds the sperm until the eggs are fully developed.
of Histeridae that are predators worth mentioning. These subclasses are known as:
1. Dendrobites
They have two common body shapes. The first type has a flatter shape; the second has a more cylindrical appearance. The former usually lives near tree barks. This is because the prey they feed on, fly
eggs, are found near tree bark. The latter also feed on insects and prefer to live in a forested area. Species of the cylindrical Dendrobites usually hunt prey that is unique for that species.
2. Geobiotes
This subclass is the most diverse and the largest of the Hister predator subclasses. The Geobites body structures are generally circular, and they are known for their digging tendencies. This subclass is separated into five more divisions. The members of this subclass live anywhere from the soil, desert, and coast to caves, mammalian burrows, and vegetation. They live in accordance with where their prey lives. One division of the Geobiote feeds on maggots and eggs that are found in forest vegetation or in carrion. Naturally, this Geobiote is found in heavily forested areas. The second and third division hunts for arthropods that feed on dead plant matter. Thus, these types of Geobiotes are found in the sand and burrowed in soil. The fourth type of Geobiotes feed on fly eggs that grow on fresh dung
. This division of Geobiotes is found near animal homes such as nests and burrows. The last type of Geobiotes lives in caves. They feed on the mites
and other arthropods that occupy the vegetation and fungi found there. This type of Geobiote is known to include species that become blind.
3. Microhisterids
This subclass is the smallest of the four. They live on plant litter and feed on the tiny arthropods found there. Microhisterids, like all other Histeridae, become specialized to hunt their prey and live in their habitats. Like the fifth division of Geobiotes, some Microhisterids are known to be blind as well.
4. Inquilines
This division consists of those Histeridae that live in close proximity with social colonies of arthropods such as ants and termites. Histeridae that live near ants can live in a harmonious or hostile relationship. The hostile Hister beetles feed on the ants. The harmonious Hister beetles eat the same food as the ants, however they may not be in direct competition for the food. These beetles have an excretory organ that produces an odor telling the ants they mean no harm.
is the study of insects related to crime scenes. Insects can be very helpful at a crime scene and give people an idea of what happened and when it happened.
Flesh eating insect
s arrive at the dead body within a few hours. Certain species of the Hister beetles follow shortly behind and prey on the maggot
s and other arthropod
s present. Insects that feed on dead bodies increase the rate of decomposition
and their mandibular mouth parts can cause excess damage to the body. Insects can also help determine the season the body died in. The Hister beetle is more prevalent in Spring and Summer.
The family, Histeridae, is very diverse, so different species can be found on the body at different times because of their various feeding habits. This needs to be noted when examining a dead body. They are predacious beetles and arrive when there is material to feed on, like other beetles or maggots. They do not actually feed on the carrion
. For example, Hister quadrinotatus and Hister sedakovi arrive to feed when the carrion is bloat to dry (full of maggots to no maggots). In contrast, Saprinus pennsylvanicus arrive at the body first, when it is fresh to late (beginning of decomposition to advanced decomposition).
The Hister beetles lay their eggs in dead bodies and over a short period of time they develop into various stages. The Histeridae larva
e are destructive and when they hatch they eat the maggots in the dead body. The stage of the beetle and other insects in the body at the time of investigation helps to determine the time of death. "Beetle larvae are ... helpful when determining post-mortem time interval. Beetle larvae often reside in fly breeding resources, and they can be distinguished from fly larvae by the following: Beetle larvae possess a hard, head capsule, often brown in colour. Fly larvae lack a head capsule, instead having distinct, internal, black mouth hooks (cephalopharyngeal skeleton of mouthparts) at the anterior end of their body." Understanding how long ago the eggs were laid and the time period of the developmental stages is important for determining the time of death.
The Histers beetles will hide under the dead body in the soil during the day and come out at night to feed. For this reason, the dead body must be examined at different times of the day. After collecting the Hister beetles from a body, isolate them because they are predacious beetles and eat anything in their way.
Family Histeridae (hister beetles)
A recent study was conducted at Hacettepe University in Ankara, Turkey. Forty species of Coleoptera, including the Hister beetles, were observed on twelve pig carcasses over a one year period. The beetles’ distribution and their time of colonization in the various decomposition stages over the year were examined and recorded.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s commonly known as Clown beetles or Hister beetles. This very diverse group of beetles contains 3,900 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
found worldwide. They can be easily identified by their shortened elytra that leaves two of the seven tergites exposed, and their elbowed antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
with clubbed ends. These predatory feeders are most active at night and will fake death if they feel threatened. This family of beetles will occupy almost any kind of niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
throughout the world. Hister beetles have proved useful during forensic investigations to help in time of death estimation. Also, certain species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are used in the control of livestock pests that infest dung
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
and to control houseflies. Because they are predacious
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
and will even eat other Hister beetles, they must be isolated when collected.
Characteristics
Thorax (insect anatomy)
The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....
with typically two of the seven tergites exposed. Hister beetles have specialized heads that can retract into their prothorax
Prothorax
The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites are the pronotum , the prosternum , and the propleuron on each side. The prothorax never bears wings in extant insects, though some fossil groups possessed...
and two elbowed antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
with clubbed ends. As predatory feeders, the Hister beetles commonly feed on the Egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, larval, and adult
Adult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....
stages of other insects. Certain species are also used to control livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
pests that infest dung or to control house flies. Histeridae are most active at night and they will play dead if they feel threatened.
Etymology
Histeridae was named by Leonard GyllenhaalLeonard Gyllenhaal
Leonard Gyllenhaal was a Swedish military officer and entomologist.Born on the Ribbingsberg manor in Västergötland in west Sweden, Leonard Gyllenhaal was son of an army officer and belonged to a family of the lower nobility...
. Histeridae has two common names, the “Clown” beetle and the “Hister” beetle. There have been several theories explaining the origin of these common names. One theory for the “Hister” nickname comes from the work of Juvenal
Juvenal
The Satires are a collection of satirical poems by the Latin author Juvenal written in the late 1st and early 2nd centuries AD.Juvenal is credited with sixteen known poems divided among five books; all are in the Roman genre of satire, which, at its most basic in the time of the author, comprised a...
, a Roman poet. Juvenal used the word “hister” to mean a dirty, lowly being. Another theory for the origin of this beetle's name stems from the fact that in Latin, “hister” means actor. Many people believe the name is associated with the Hister beetles’ ability to imitate death when they are disturbed. Still, some believe this family of beetles was named for its physical characteristics. The Clown beetle has flattened legs, which can be compared to a clown’s flat shoes or loose-fitting pants.
Anatomy
The Histeridae family is diverse. They rarely get over ten millimeters in length. The body form of these beetles is typically rounded or ovoid, but some are flat and rectangular. Typical coloration patterns include black, metallic green, and black with red markings.As with all insects, the body consists of a head, thorax, and abdomen. The thorax is divided into the prothorax, mesothorax
Mesothorax
The mesothorax is the middle of the three segments in the thorax of an insect, and bears the second pair of legs. Its principal sclerites are the mesonotum , the mesosternum , and the mesopleuron on each side...
and metathorax
Metathorax
The metathorax is the posterior of the three segments in the thorax of an insect, and bears the third pair of legs. Its principal sclerites are the metanotum , the metasternum , and the metapleuron on each side...
; the dorsal side of the prothorax is a sclerotized shield, the pronotum. The Hister beetle has an exoskeleton
Exoskeleton
An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...
made of chitin
Chitin
Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world...
which gives protection to the internal organs. The elytra and forewings are normally well developed in beetles, but in Histerdiae the elytra are shortened and rectangular. The shortened elytra expose the final two of the seven tergites. Attached to the body are three pairs of jointed legs and two pairs of wings. The head has compound eyes, a mandible mouthpart
Insect mouthparts
Insects exhibit a range of mouthparts, adapted to particular modes of feeding. The earliest insects had chewing mouthparts...
, and shortened antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
. The eyes do not move; each takes a little piece of the picture to make a complete picture. The Hister's mouthpart grasps and grinds the food with two teeth. Lastly, the antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
work as sensory organs. A distinctive characteristic is that the antennae are elbowed and contain three antennomeres that form a club at the end.
Clown beetles have an open circulatory system
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
within its hemocoel, also known as a body cavity. They have a tube shaped heart that spans the length of the body, and use hemolymph
Hemolymph
Hemolymph, or haemolymph, is a fluid in the circulatory system of some arthropods and is analogous to the fluids and cells making up both blood and interstitial fluid in vertebrates such as birds and mammals...
as blood. This blood does not contain any oxygen, but carries nutrients throughout the body. Spiracles are located on the abdomen and are the tracheal system of the beetle. Oxygen is brought into the body by spiracles and tiny sacks exchange the oxygen like a mammal's lung. The beetles digestive system is known as an alimentary canal. The digestive system feeds the circulatory system. Within the canal, food and water are broken down, absorbed and excreted.
Habitat
Hister beetles are found throughout the world in various habitats. Histeridae have been located in North America, Central America, Europe, Asia, and Australia, but each Hister beetle occupies certain niches. The beetles live in dung, carrionCarrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
, dead vegetation, sandy areas, under tree bark, mammal burrows, and ant/termite colonies. Charactertistics of the Hister beetle are dependent upon its habitat. For example, the flat Hister beetles are found under bark, while the cylindrical beetles are not. Shape of the beetle will vary from species to species.
A unique ability of the Hister beetle is their capacity to live in close proximity with ants (myrmecophiles) and termites (termitophiles). The Hister beetles can live in harmony with the ants or predate on the ants, depending on the species.
Histeridae’s habitat is wide spread because they feed on other arthropods. As new food sources are introduced into an environment, the predators of that food source will soon follow. Histeridae live in areas where their prey feed. Some examples are mammalian nests where other arthropods scavenge for food or carrion where maggots will arrive.
Feeding habits
The larvae and adult forms of Histeridae have been known to feed on dung, carrion, decomposing vegetation, other insects, larvae, and pupae. The Hister beetles are able to locate both dung and carrion through olfactionOlfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...
. When found on dung, carrion and vegetation, the Hister beetles will feed on the fly larvae found there. The predacious Hister beetle will feed on soft-bodied insect eggs and larvae, Diptera
Diptera
Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...
in particular. Some species of Histeridae will even feed on other Histeridae.
The majority of Histeridae species prefer dried, decaying habitats. When found on carrion the adult Histeridae will usually be feeding on Diptera maggots, not the rotting material. The larvae of Hister beetles feed on the blowfly pupae found on the body.
Some Histeridae species live in an integrated nest with ants and termites. Some species have been found to be fed by the ants, while others simply feed on leftover insect larvae that the ants do not want. In contrast, in their adult stage Psiloscelis will actually feed on adult ants.
Because the Histeridae are predacious they can be utilized as control agents, but must be stored in isolation. The Hister beetles have proven useful in both the control of pest flies in poultry houses and pastures, and against pest beetles of stored food products.
Development
Histeridae goes through holometabolous developmentHolometabolism
Holometabolism, also called complete metamorphism, is a term applied to insect groups to describe the specific kind of insect development which includes four life stages - as an embryo or egg, a larva, a pupa and an imago or adult. Holometabolism is a monophyletic trait that all insects in the...
. In this type of development the larval form does not resemble the adult form and the pupae has internally developing wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...
s. They also undergo an immobile pupal stage where they do not eat. After the pupal stage they emerge in their adult form.
The Histeridae life cycle consists of egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, larval, pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
l and adult
Adult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....
stages of development:
Egg
The average time of development from EggEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
to adult
Adult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....
at 30 degrees celsius is 20.5 days. The eggs of most species are off-white and oval in shape. The egg takes on average 3.8 days +/- 0.02 to develop into the first instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
. The chorion
Chorion
The chorion is one of the membranes that exist during pregnancy between the developing fetus and mother. It is formed by extraembryonic mesoderm and the two layers of trophoblast and surrounds the embryo and other membranes...
is shiny and smooth. In certain species like epirerus or platylomalus it can look pale brown and be leathery in texture.
Larval
The larval stage of the beetle typically goes through two instars, the second instarInstar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
is the longest stage of its entire development, taking up 39% of the overall development time. It takes 5.1 days +/- 0.1 on average for the first instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
to develop into the second. The larval form of the insect will range in length from three millimeters to several centimeters. They have a membranous body with a limited amount of sclerotization around the head. There is some pigmentation around the body and it is horizontally segmented. The legs are short and do not help much in locomotion
Animal locomotion
Animal locomotion, which is the act of self-propulsion by an animal, has many manifestations, including running, swimming, jumping and flying. Animals move for a variety of reasons, such as to find food, a mate, or a suitable microhabitat, and to escape predators...
. They move mostly through muscular contraction.
Pupal
The pupal form of the beetle is similar in appearance to the adult form. They have outer cells produced in the larval stages that are reinforced with proteinaceous cement. This makes their outer shell harder and protects them during this vulnerable stage. While they pupate they breathe through spiracles on the abdomen. The beetle is non-feeding and immobile in this stage, as their internal structure is breaking down and rebuilding to its adult form. Under good temperature conditions the Hister beetle will stay in the pupal stage for about a week.Male and Female Structures
The male and female reproductive organs are hidden underneath the last few sternites on the mesosternal (mesosternum) side. The female's structure is modified to work as an ovipositorOvipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
while the male's is adapted as a copulatory structure. The female has oviducts that carry the developed eggs from the ovaries to the ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
. The males also have a duct that carries the sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
from the testes to the copulatory structure, which stays concealed until copulation. When fertilization takes place, the male leaves enough sperm in the female to fertilize all the eggs in the female's ovaries. The excess sperm is kept in a special structure called spermatheca
Spermatheca
The spermatheca , also called receptaculum seminis , is an organ of the female reproductive tract in insects, some molluscs, oligochaeta worms and certain other invertebrates and vertebrates...
which holds the sperm until the eggs are fully developed.
Subclasses
There are four subclassesClass (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
of Histeridae that are predators worth mentioning. These subclasses are known as:
1. Dendrobites
They have two common body shapes. The first type has a flatter shape; the second has a more cylindrical appearance. The former usually lives near tree barks. This is because the prey they feed on, fly
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
eggs, are found near tree bark. The latter also feed on insects and prefer to live in a forested area. Species of the cylindrical Dendrobites usually hunt prey that is unique for that species.
2. Geobiotes
This subclass is the most diverse and the largest of the Hister predator subclasses. The Geobites body structures are generally circular, and they are known for their digging tendencies. This subclass is separated into five more divisions. The members of this subclass live anywhere from the soil, desert, and coast to caves, mammalian burrows, and vegetation. They live in accordance with where their prey lives. One division of the Geobiote feeds on maggots and eggs that are found in forest vegetation or in carrion. Naturally, this Geobiote is found in heavily forested areas. The second and third division hunts for arthropods that feed on dead plant matter. Thus, these types of Geobiotes are found in the sand and burrowed in soil. The fourth type of Geobiotes feed on fly eggs that grow on fresh dung
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
. This division of Geobiotes is found near animal homes such as nests and burrows. The last type of Geobiotes lives in caves. They feed on the mites
MITES
MITES, or Minority Introduction to Engineering and Science, is a highly selective six-week summer program for rising high school seniors held at the Massachusetts Institute of Technology. Its purpose is to expose students from minority, or otherwise disadvantaged backgrounds, to the fields of...
and other arthropods that occupy the vegetation and fungi found there. This type of Geobiote is known to include species that become blind.
3. Microhisterids
This subclass is the smallest of the four. They live on plant litter and feed on the tiny arthropods found there. Microhisterids, like all other Histeridae, become specialized to hunt their prey and live in their habitats. Like the fifth division of Geobiotes, some Microhisterids are known to be blind as well.
4. Inquilines
This division consists of those Histeridae that live in close proximity with social colonies of arthropods such as ants and termites. Histeridae that live near ants can live in a harmonious or hostile relationship. The hostile Hister beetles feed on the ants. The harmonious Hister beetles eat the same food as the ants, however they may not be in direct competition for the food. These beetles have an excretory organ that produces an odor telling the ants they mean no harm.
Importance in forensics
Forensic EntomologyForensic entomology
Forensic entomology is the application and study of insect and other arthropod biology to criminal matters. It is primarily associated with death investigations; however, it may also be used to detect drugs and poisons, determine the location of an incident, and find the presence and time of the...
is the study of insects related to crime scenes. Insects can be very helpful at a crime scene and give people an idea of what happened and when it happened.
Flesh eating insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s arrive at the dead body within a few hours. Certain species of the Hister beetles follow shortly behind and prey on the maggot
Maggot
In everyday speech the word maggot means the larva of a fly ; it is applied in particular to the larvae of Brachyceran flies, such as houseflies, cheese flies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and Crane flies...
s and other arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s present. Insects that feed on dead bodies increase the rate of decomposition
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
and their mandibular mouth parts can cause excess damage to the body. Insects can also help determine the season the body died in. The Hister beetle is more prevalent in Spring and Summer.
The family, Histeridae, is very diverse, so different species can be found on the body at different times because of their various feeding habits. This needs to be noted when examining a dead body. They are predacious beetles and arrive when there is material to feed on, like other beetles or maggots. They do not actually feed on the carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. For example, Hister quadrinotatus and Hister sedakovi arrive to feed when the carrion is bloat to dry (full of maggots to no maggots). In contrast, Saprinus pennsylvanicus arrive at the body first, when it is fresh to late (beginning of decomposition to advanced decomposition).
The Hister beetles lay their eggs in dead bodies and over a short period of time they develop into various stages. The Histeridae larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e are destructive and when they hatch they eat the maggots in the dead body. The stage of the beetle and other insects in the body at the time of investigation helps to determine the time of death. "Beetle larvae are ... helpful when determining post-mortem time interval. Beetle larvae often reside in fly breeding resources, and they can be distinguished from fly larvae by the following: Beetle larvae possess a hard, head capsule, often brown in colour. Fly larvae lack a head capsule, instead having distinct, internal, black mouth hooks (cephalopharyngeal skeleton of mouthparts) at the anterior end of their body." Understanding how long ago the eggs were laid and the time period of the developmental stages is important for determining the time of death.
The Histers beetles will hide under the dead body in the soil during the day and come out at night to feed. For this reason, the dead body must be examined at different times of the day. After collecting the Hister beetles from a body, isolate them because they are predacious beetles and eat anything in their way.
Genus and species
Histeridae is a family of beetles. It is a large and diverse family. There are approximately 3,900 species and about 500 of them are located in the United States. The beetles range in size, shape and color. Many of the adults are predacious. This is a brief taxonomy list of a few genus and species.Family Histeridae (hister beetles)
| Gensus | Species | Pictures |
|---|---|---|
| Abraeomorphus | Abraeomorphus atomarius | |
| Atholus | Atholus rothkirchi | |
| Aeletes | Aeletes angustisternus Aeletes angustus Aeletes basalis Aeletes concentricus Aeletes eutretus Aeletes facilis Aeletes flavitarsis Aeletes germanus Aeletes insolitus Aeletes kauaiensis Aeletes kukuiae Aeletes laevis Aeletes lanaiensis Aeletes longipes Aeletes makaweliae Aeletes mauiae Aeletes minor Aeletes molokaiae Aeletes monticola Aeletes nepos Aeletes ornatus Aeletes parvulus Aeletes perkinsi Aeletes pulchellus Aeletes punctatus Aeletes sculptus Aeletes similis Aeletes solitarius Aeletes subalatus Aeletes subbasalis Aeletes subrotundatus Aeletes waianaae |
|
| Acritus | Acritus komai Acritus minutus |
 |
| Bacanius | Bacanius confusus Bacanius dentrecasteauxi Bacanius rombophorus |
|
| Carcinops | Carcinops pumilio | |
| Geomysaprinus | Geomysaprinus goffi | |
| Hololepta | Hololepta minuta Hololepta plana Hololepta quadridentata |
 |
| Hister | Hister abbreviatus Hister bimaculatus Hister coenosus Hister confinis Hister javanicus Hister nomas Hister orientalis Hister quadrimaculatus |
 |
| Neopachylopus | Neopachylopus sulcifrons | |
| Platylomalus | Platylomalus gardineri | |
| Pachylister | Pachylister caffer Pachylister chinensis Pachylister lutarius |
|
| Plaesius | Plaesius javanus | |
| Paromalus | Paromalus lautus |  |
| Saprinus | Saprinus fimbriatus Saprinus lugens |
Current research
Because the Histeridae family can be found on carrion, they have proven to be important in certain forensic investigations. The predacious Hister beetles will feed on the various insects on the body, primarily Diptera. To estimate a person's time of death, forensic investigators must look at the insects on the body and determine time of colonization. If the Histeridae beetles are present, the investigator can assume that some of the other insects have been eaten by the Hister beetles. Due to their importance in forensic entomology, research is continually being conducted on this family's life cycle and development, their prevalence in specific locations, and their geographical distribution.A recent study was conducted at Hacettepe University in Ankara, Turkey. Forty species of Coleoptera, including the Hister beetles, were observed on twelve pig carcasses over a one year period. The beetles’ distribution and their time of colonization in the various decomposition stages over the year were examined and recorded.