This diary has languished in draft form, unfinished but not forgotten, for several months. ?It was the original attempt to blog about insect diversity and it will now be the fourth diary in the arthropod diversity series. ?As always the purpose of these diaries is to provide a research for the Backyard Science group and other interested folks. ?Monitoring the changes in biodiversity caused by a changing environment requires that you know what you're looking at. ?These diaries are designed to be a tool to complement the excellent bug guide web site. ?
In this entry in the series we are taking the bull by the horns so to speak and tackling one of the really big insect orders: the Hymenoptera. ?This group currently has well over 100,000 named species (approximately 25 species for every species of mammal on earth) or about 10% of all (named) animal species. ?So there is no way they can be covered in the same level of detail as I did for the Orthoptera in the previous diary. ?Hopefully the level of coverage that is possible will still be useful. ?The material above the orange squiggle is a general introduction to the Hymenoptera, below the squiggle is detailed nitty gritty of identifying different groups.
Ants, Bees, and Wasps?
Ants represent a single family within the order, bees a group of several closely related families. ?And then there is the thorny question of wasps. ?What is a wasp? ?Entomologists can't agree exactly how the word should be applied. ?The problem is that wasp is an informal 'trash bin' taxonomic group. ?If you want to apply the term very broadly then any insect in the order Hymenoptera that isn't a bee or an ant is a wasp. ?More narrowly you could say that any member of the subgroup of the Hymenoptera called the Aculeata (Hymenoptera with stingers) that isn't an ant or bee is a wasp. ?I'm going to sit on the fence and take a middle position. ?The Aculeata is part of a larger group called the Apocrita (see below for details) - I'm going to refer to any member of the Apocrita that is not explicitly a bee or an ant as a wasp. ? Most wasps encountered by average person are going to be in the Aculeata so that is where I will focus the bulk of the diary.
Social Behavior
The Hymenoptera are renowned for their complex social behavior. ?Although the species that are eusocial (see below) make up a minority of the species the social species are enormously ecologically important and also very conspicuous. ?Naturalists, writers, and just average folk have been fascinated by the highly cooperative nature of these insects for a very long time. ?A detailed discussion of social behavior will have to wait for a different diary but I will offer a brief overview.
Sociality can be classified on the following scale. ?Non-social organisms would have no interactions with members of their own species beyond mating. ?
Subsocial - parents care for their own offspring solitarily
Communal - parental care occurs in groups but each parent cares exclusively for her own offspring.
Quasisocial - shared parental care within the group but all members of the colony reproduce
Semisocial - Only some members of the colony reproduce but which members are reproductive may change over time or the colonies may be of short duration.
Eusocial - Meets three criteria. ?Cooperative care of offspring. ?Reproductive division of labor (only some individuals reproduce). ?Multiple generations of adults in the same colony.
Thus, Hamilton's work predicts that you should see individuals forgoing reproduction to help care for other individual's offspring when one of more of the following are true: ?the individuals involved are closely related (r is high), the helping individuals have a low probability of successful reproduction even if they don't help (c is low), and/or the number of offspring an individual can produced is greatly increased through helping (b is high).
Two competing (but not necessarily mutually exclusive) hypotheses have been proposed to explain the high frequency of eusocial species in the Hymenoptera compared to other groups of animals. ?One is a genetic hypothesis based on the unusual mechanism of sex determination in all Hymenoptera. ?They are haplodiploid. ?Males are haploid (have only a single set of chromosomes) and develop from unfertilized eggs. ?Females are diploid and develop from fertilized eggs. ?One consequence of this is that full sisters in this situation share an unusually high proportion of their genes (75% as opposed to 50% in a 'normal' system) and are thus in a sense more closely related to their sisters than to their daughters. ?So r is unusually high among related females in the Hymenoptera.
The other hypothesis is an ecological hypothesis based on the high frequency of nesting behavior in one group of Hymenoptera, the Aculeata. ?This is the only group that has social species. ?It has been proposed that in colonially nesting species some individuals may be excluded from reproduction by social dominance. ?Their chances of reproducing on their own, away from the colony, are very low and thus their best option is to help relatives. ?So the argument here is that c is low.
Larval Biology of the Hymenoptera
One of the really cool things about insects is that so much of their ecology and evolutionary history is driven by larval biology. ?Some insects have juvenile stages (nymphs) that are similar to the adults. ?For example a juvenile grasshopper looks just like an adult grasshopper - it just lacks wings and genitalia. ?However, most insects have a larval stage that is completely different from the adult stage and a pupal stage that reorganizes the body between the two stages. ?It's as if the kids are a completely different type of life than the adults. ?I'm childless but my understanding is that the parents of teenagers often feel this way. ?However in insects this more than just a saying - it is literally true.
Larval characteristics often strongly influence adult biology. ?Adults are more mobile and can seek out appropriate places to lay eggs where the larvae can thrive. ?In the Hymenoptera the evolution of larval form has resulted in some really fascinating phenomena in the adults such as: parasitism, gall-forming, parental care, and complex societies.
Many of the Hymenoptera are parasitoids. ?The larvae live inside their hosts (insects or spiders) and eventually kill them. ?The adult females will deposit eggs on the host. ?Adults of these species are not parasites. ?When a group is called parasitic later in the diary it is the larvae that are parasites.
A short transition for parasitism is found in species in which the females capture prey and provide to larvae in nests.
Taxonomy
Bugguide splits the Hymenoptera into three groups: ?the 'Symphyta', the 'Parasitica', and the Aculeata. ?These are not given any formal taxonomic rank. ?Note that the terms 'Symphyta' and 'Parasitica' are written in quotation marks. ?This indicates that they are not what are called natural (or more technically, monophyletic) groups. ?What does this mean? ?I'll explain in the paragraph below. ?If you don't really care you can skip over it and read the descriptions of the groups below the swirly orange thing.
A natural group is a self-contained evolutionary unit. ?In other words it is all the descendants of a common ancestor. ?The original Hymenopterans were organisms that resembled the current members of the 'Symphyta'. ?One branch(the Apocrita) evolved a different body form resulted in a huge amount of evolution resulting in all the rest of the Hymenoptera. ?The 'Parasitica' and the Aculeata are both part of the Apocrita. ?Some of the 'Symphyta' are quite closely related to the 'Parasitica' and Aculeata and some are more distantly related. ?However they are all grouped together because they retain the ancestral form. ?Similarly within the 'Parasitica' there are some groups that are more closely related to the Aculeata than others. Taxonomists generally frown on groups that are not natural but they can be quite useful in a descriptive context. ?
Identification of the Hymenoptera to One of Three Major Groups in Bug Guide ('Symphyta', 'Parasitica' and Aculeata)Thorax and abdomen broadly connected as in most insects. ?Larvae resemble caterpillars - 'Symphyta'
Thorax and abdomen with a narrow connection (may be difficult to see in living examples of robust insects such as bees). ?Apocrita ('Parasitica' and Aculeata combined).
Body form highly variable but often somewhat wasp-like. ?For the most part very small insects. ?Ovipositor may be long but is not a retractable stinger. ?Larvae are maggot-like and parasitize other arthropods or live inside plants. ?- 'Parasitca'
Body form resembles an ant, bee, or wasp. ?Ovipositor forms a retractable stinger. ?Larvae are maggot-like and are provided with food by adults in most species. - Aculeata.
The Apocrita differ from the 'Symphyta' in two ways. ?They have a very narrow connection between their thorax and abdomen. ?Technically the first section of the abdomen is fused with the thorax so the waist is actually within the abdomen but this won't be obviously without a really close look. ?In ants and many wasps this gives them a characteristic narrow 'waist'. ?Note: the waist and the back part of the middle part of the body are actually part of the abdomen. ?So to be technically correct Hymnopterists refer to the middle part of the body as the Mesosoma and the hind part as the Metasoma. ?I am going to use the terms Thorax and Abdomen although they are technically incorrect as they will be more familiar to my intended audience ?If both the thorax and the abdomen are thick and close together the waist may not be apparent without some examination. ?The other difference is that their larvae are grub like, lacking both legs and a distinct head. ?The Apocrita are divided into the Aculeata and 'Parasitica' as discussed above.
I am going to discuss these three groups in reverse order. ?Most of the Hymenoptera that the average person will encounter are members of the Aculeata. ?The 'Symphyta' can be fairly easily distinguished from other Hymenoptera and they make up a small proportion of the total species. ?As they are encountered much less frequently than the other two groups I will discuss them last. ?Other than the stinger there isn't a good single definitive and easily seen characteristic that will distinguish the Aculeata from the 'Parasitica'. ?What I would recommend is if the insect looks distinctly like an ant, bee, or wasp then start with the assumption that it is a member of the Aculeata. ?If it looks vaguely wasplike but is really tiny or has a long ovipositor or is otherwise oddly shaped you can start with the assumption it is a member of the 'Parasitica'
The Aculeata is a subgroup of the Apocrita in which the egg-laying organ (the ovipositor) is modified as a stinger. ?Eggs are laid through an opening at the base of the ovipositor which has lost its original function. ?Any member of the Aculeata, that is not a bee or an ant is definitely a wasp.
The Pronotum: A key characteristic in distinguishing groups of Aculeata and 'Parasitica'
Images in this section are all from Wikimedia Commons.
The pronotum is the part of the exoskeleton that forms the back of the insect immediately behind the head. ?In many such as beetles and grasshoppers the pronotum is a large structure that covers the entire back of the insect down to the base of the wings. ?In the Hymenoptera the pronotum is smaller and its shape is useful in distinguishing among different groups. ?In mid-size to large insects that are not covered in hair this should be fairly easy to see in a reasonable photograph.
The default situation, found in all the 'Parasitica' and Aculeata other than those mentioned below is to have a pronotum that is triangular side pieces connected by a narrow bend across the top which is generally not visible. ?So if you look at the insect from the side the pronotum will appear triangular with one point extending back to the base of the wings. ?From the top in these insects the pronotum is usually not visible as it is hidden in the neck region of the insect. ?A diagonal line sloping back and down from the neck to the base of the wings should be visible on both sides. ?The image of the paper wasp below shows the triangle clearly.
In the two different groups of Apoidea (bees and the Apoid wasps) the pronotum is narrow and is clearly set apart from the rest of the thorax to form a distinct collar. ?This is often very easy to see in the wasps (sometimes it is a different color than adjacent parts of the insect) but can be harder to see in bees. ?The picture below shows an Apoid wasp (Crabronidae) drinking water. ?The collar is immediately behind the head.
In a few other groups of Hymenoptera such as the superfamily Chalcidoidea in the 'Parasitica', the superfamily Chrysidoidea in the Aculeata and some of the Vespoidea the pronotum is wide all the way across so that it appears square when viewed from the side. ?The picture of the Chrysidid wasp below clearly shows a broad segment right behind the head of the insect.
?Groups of the AculeataSuperfamily Chrysidoidea
This is by far the smallest of the major groups the Aculeata. ?They can be distinguished from the other groups (for the most part) by their wide pronotum with a back edge that is straight all the way across. ?There are only two families that are likely to be found. ?Members of the this superfamily are all parasitic and do not provide parental care.
Family Chrysididae - Cuckoo Wasps. ?These are small wasps that are usually bright metallic blue or green. ?Their exoskeleton is often sculptured or pitted. ?Two other groups of Hymenoptera could be mistaken for Cuckoo Wasps. ?Several different families within the Chalcidoidea (a superfamily in the 'Parasitica') often have metallic colors and one (the Perilampidae) has similar pitting/sculpturing of the exoskeleton. ?Chalcidoids have a similar shape of pronotum to Cuckoo Wasps but they differ in two key respects. ?First Chalcidoids are generally smaller although there is some overlap in size. ?Secondly the wings of Chalcidoids have almost no veins in them. ?The other group are the Sweat Bees (Halictidae). ?Some sweat bees have bright metallic coloration but they will have more hair and more veins in the their wings.
Family Bethylidae - Small black wasps that superficially resemble ants. ?Females are often wingless. ?Could be mistaken for many families in the 'Parasitica' but the elongate head and body are characteristic.
Superfamily Apoidea 1: Apoid Wasps ?This very large group was formerly considered a single family, the Sphecidae. ?Studies have resulted in the split of this group into multiple families. ?Two of the three families listed in Bugguide are likely to be encountered. ?Body form is quite variable but all should be recognizeable by the collar-like pronotum. ?Almost all of these wasps have nests and bring insects or spiders to the nests as food for their larvae. ?The type of prey and nest are typical of each subfamily.
Mostly solitary insects but some build nests in groups without cooperation in rearing of offspring. ?Some tropical species are social.
Family Crabronidae - Contains about 90% of the species in North America. ?Highly variable in color but many of them have coloration resembling that of a bee or yellow jacket. ?The most famous species in this family are the Cicada Killers in the genus _ Sphecius_, very large wasps of formidable appearance that prey on cicadas. ?Most Crabronids nest in the ground and are moderately heavy bodied but the organ pipe mud dauber builds mud nests (resembling organ pipes) above ground and is a more slender insect.
Family Sphecidae - Thread-waisted wasps. ?A much smaller but distinctive and commonly seen family. ?The obvious characteristic is the extremely long narrow waist attaching the abdomen to the rest of the body. ?Contains both mud-daubers and ground nesters. ?Most commonly all black but color is variable.
Superfamily Apoidea 2: Bees ?The bees are a very large and successful group. ?They are fairly heavy-bodied Hymenoptera with lots of hair. ?The hairs are branched.
Most bee species are not social, although all bees, except for species that lay their eggs in the nests of other bees, care for their offspring in nests. ?Social behavior has evolved many times in within the bees which makes them a group of particular interest to evolutionary biologists. ?Many of the solitary bees have nests that occur in aggregations (many nests close to one another but not physically connected) or colonies (nests have a common entrance but each female has her own nest and there is no sharing of parental care). ?Most bees collect pollen to feed their larvae.
One family, the Mellitidae is uncommon and will not be covered.
Three of the remaining families are solitary bees that mostly nest in the ground. ?They are:
Family Andrenidae - Mining Bees. ?Dark brown bees that more or less look like a honey bee except for the color. ?Nest in tunnels in the ground, often in colonies
Family Colletidae ?- Yellow-faced Bees and Plasterer Bees. ?Ground nesters. ?Plaster Bees are hairy with dark and light bands on the abdomen. ?Often fairly light colored. ?Yellow-faced bees are largely hairless and look more wasp-like. ?They have distinct yellow marks on their faces.
Family Megachilidae - Leaf cutting Bees. ?Stout and fairly dark bees with yellow or red markings. ?Leaves are used to line the walls of the nest (in ground or in wood). ?Pollen is carried on the underside of the body rather than on the legs.
The next family is the Halictidae or Sweat Bees although only some of the species are attracted to perspiration. ?They are small to midsize bees that are quite variable in color. ?Many are dark but some have 'typical' bee and wasp banding and others are partly or completely metallic green.
These bees nest in the ground and are frequently colonial. ?Simple social behavior has evolved several times in this family.The remainder of the bees are in the family Apidae which includes all the highly social bees as well as others. ?Honey bees and Bumble Bees are highly social. ?Bumble bees nest in the ground in small annual colonies. Carpenter bees are either solitary or primitively social and have nests in wood. ?Small Carpenter Bees resemble Halictid bees while large Carpenter bees resemble bumble bees (some large Carpenter Bees are very large indeed) but the tops of their abdomens are hairless and shiny. ?Cuckoo bees are wasplike mostly hairless bees that lay their eggs in the nests of other bees. ?There are other solitary members of this family that look like Honey and/or Bumble bees in a general sense.
Superfamily Vespoidea ?This group is more or less a grab-bag of families that do not belong in the other groups and thus these families may not all be closely related. ?Some families are parasitic while others care for their offspring. ?Two families have highly social species. ?We will only consider seven of the eleven families listed in bugguide. ?The rest are rare and not likely to be encountered.
Family Scoliidae - Large hairy wasps. ?Distinctly wasplike in shape but with much more hair than most wasps. ?Parasites of beetle larvae.
Family Tiphiidae - Medium-sized parasitic wasps. ?This is a hard group to characterize. ?Many are all dark and often have the segmentation of the abdomen more apparent than in most wasps. ?Others are banded black and yellow and superficially resemble wasps in other families. ?Some have wingless females that look vaguely like ants.
Family Bradynobaenidae - These wasps resemble the velvet ants and were formerly classified with them. ?If you have what you think is a velvet ant you might try this family as well.
Family Mutilidae - Velvet Ants - Parasitic wasps with winged males and wingless females. ?Resemble large hairy ants and are often very brightly colored. ?Females have a very painful sting (so I'm told). ?Females are seen much more often than males.
Family Pompilidae - Spider Wasps - Solitary wasps that capture prey and care for their offspring in nests. ?Therefore similar in ecology to the Sphecoid wasps but similar in appearance to the Vespidae. ?Have long hind legs, usually a dark body and frequently dark wings. ?Medium-sized to very large wasps. ?The western 'tarantual hawks' are very large spectacular insects.
Family Formicidae - Ants - This is one of the most familiar groups of Hymenoptera and indeed of all insects. ?All ants are eusocial and live in long term colonies, some of which are very large. ?Non-reproductive ants and wingless and the winged reproductives tear off their wings when they found colonies. ?Although ants are familiar insects there are a number of other insects that resemble them. ?Ants have elbowed antennae. ?They also have one or two small bumps coming of the back of the waist (i.e. between the thorax and abdomen).
Family Vespidae - Social Wasps and Relatives - This is the group that first comes to mind when you think of wasps. ?There are several subfamilies of solitary wasps in the Vespidae. ?They are variable in appearance but generally look something like a yellow jacket or hornet. ?They build nest in the ground, out of mud, or of paper with each female caring for her own offspring but bringing them a characteristic type of insect prey. ?The Eumarinae - Potter and Mason Wasps is by far the most common subfamily of solitary Vespids. ?The two social subfamilies are the Polistinae and Vespinae. ?The Polistinae are the paper wasps. ?They have relatively small colonies that live in a paper structure with open cells in which the larvae are found. ?North American paper wasps are most usually brown and yellow although there is some variation. ?They are slender insects with a very pronounced waist. ?The Vespinae are the yellow jackets and hornets. ?They are black alternating with either white or yellow. ?Their colonies occur either in the ground (yellow jackets) or in enclosed, roughly spherical paper colonies (aerial yellow jackets and hornets).
All of the Apocrita (narrow-waisted Hymenoptera) that aren't Aculeata (stinging Hymenoptera) belong to the informal group known as the 'Parasitica'. ?The name derives from the fact that most of the insects in this group are parasitoids. ?Most species lay eggs on or in their hosts, most commonly larval insects, the larvae live inside the host eventually killing it once the larval or pupal stage is complete. ?
The Parasitica is a huge group of insects. ?In addition to the parasitoids it includes some species that primarily feed on plants such as the fig wasps and the oak gall wasps. ?Many of the parasitic species are used as biological control of pest insects. ?However they are generally not conspicuous insects. ?Although a few, such as some of the Ichneumonid wasps are quite sizable, most are small insects. ?Typically they are around the size of a fruit fly and some are among the smallest known insects. ?For the most part they do not occur in groups or seek out humans, our food or our structures. ?So we don't tend to notice them.
Major groups of the 'Parasitica'
There are no fewer than 10 superfamilies within the 'Parasitica'. ?We will divide them into three groups based on diversity.
Group 1. Highly abundant and diverse insects - should be considered first.
1. Have long threadlike antennae with at least 16 segments apiece, usually slender insects sometimes with a long conspicuous ovipositor. ?Wings have substantial venation. ?Highly variable in size with some large species - Superfamily Ichneumonoidea.
This group is by far the most likely to be encountered within the 'Parasitica'. There are two families: the Ichneumonidae and the Braconidae. ?The two families are very similar, differing only in the venation pattern of the wings. ?The Braconidae are exclusively small insects while some of the Ichneumonidae get fairly large. The Ichneumonidae is largest family of insects in North America, probably containing more species than all the rest of the 'Parasitica' combined. ?Less abundant groups with an Ichneumon body form include families in the Evanoidea, Diapriodea, and the Proctotrupoidea.
2. Small insects with elbowed antennae. ?Have a stockier body than the Ichneumonoidea. ?Little or no wing venation. ?Variable in shape but generally stockier insects than the Ichneumenoidea. ?Highly variable in color, often with iridescence. - Superfamily Chalcidoidea.This group contains no fewer than 17 families in North America. ?Almost all of the Chalcidoidea are very small insects and will be next to impossible to identify without access to a high quality microscope. ?Two of the families, the Mymaridae and the Trichogrammatidae, are specialists that parasitize the eggs of other insects and spiders and are among the smallest of all known insects. ?Some adults are less than 1 mm long. ?We'll briefly mention the most numerous families as well as a few of the more distinctive and easily recognized ones.
The Eulophidae and the Pteromalidae are the two largest families. ?They are very similar in general appearance. ?Eulophids have four segmented feet (4 tarsal segments) while Pteromalids have five segments.
There are several families that are more easily recognized. ?The Torymidae have long ovipositors. The Chalcididae and Leucospidae are relatively large for Chalcidoidea. ?Both families have a greatly enlarged femur on each of the hind legs giving them the look of 'popeye arms'.
3. Small insects with threadlike antennae. ?Usually have an oval abdomen and a hunched back and little wing venation. ?Superfamily Cynipoidea
This is a large and common group. ?Almost all the species are in the family Cynipidae, the gall wasps. ?The larvae live in plant growths (galls) that are induced by the insects. ?Most commonly these galls are found on oaks. ?Each species of gall wasp has a characteristic type of gall on a particular host plant.
Group 2 - Common insects but much less likely to be encountered than group 1.
4. Variable sized insects with threadlike antennae and wings with veins. ?Abdomen attached to rest of body fairly high on the back of the thorax. ?Many species resemble members of the Ichneumonoidea but have a pronounced neck separating the head and thorax - Superfamily Evanoidea
This group is somewhat smaller than the previous three. ?It contains two families, the Aulacidae and the Gasteruptiidae, that closely resemble Ichneumon wasps but have the head attached to the thorax with a distinct neck. ?A third family, the Evaniidae, are bizarre, unmistakeable insects that are parasitoids of cockroach egg cases. ?They are black and spider like with a tiny abdomen that hangs of the back of the large thorax like a flag, giving them the common name of Ensign wasps.
5. Small, somewhat elongate, shiny black insects with long threadlike antennae that arise from shelf-like projection in the middle of the face- Superfamily Diaprioidea
There is only a single family, the Diapriidae.
6. Tiny black insects with elbowed antennae that arise very low on the face and flattened abdomens. ?Superfamily Platygasteroidea
There is only a single family, the Platygasteridae.
7. Tiny black insects similar to the Platygasteroidea but with a more rounded abdomen. - Superfamily Ceraphronoidea
8. Superfamily Proctotrupoidea. ?Contains two distinctive families that are considered separately below
Very large (two inches!) with a extremely long, thin abdomen (superficially resembles a damselfly) - family Pelecinidae. ?Only a single species in eastern North America.
Small slender insects with long threadlike antennae and a spindle-shaped (i.e. tapered at both ends) abdomen that is often a different color than the rest of the body. ?In many species the tail end of the abdomen bends downward as well as tapering. - family Proctotrupidae.
Group 3. ?The remaining two superfamilies, the Stephanoidea and the Trigonaloidea are rare insects that are unlikely to be encountered.
The 'Symphyta' are the sawflies and horntails. ?This is a fairly small group of organisms relative to the other two. ?They are vaguely wasplike in appearance but the thorax and abdomen are broadly joined (i.e. there is no waist like you clearly see in ants or in paper wasps, etc.). ?Unfortunately I am not familiar with the Symphyta. ?There are quite a few families but most of them are very small with only a handful of species in North America.
By far the most common family are the Tenthredinidae. ?These are mid-sized insects that resemble a reasonably heavy-bodied wasp with a broad head. ?The antennae are moderately long and thread-like. ?The larvae are often plant pests.
A particularly striking family in the 'Symphyta' is the Siricidae or Horntails. ?These are large insects (up to two inches) with a cylindrical body and an abdominal spine. ?The larvae feed on wood.
The Argidae are stout-bodied insects with distinctive three-segmented antennae with the first segment being very long.
The Diprionidae are the Conifer Sawflies. ?They are stout and have plumed antennae. ?Common in areas where in conifers are common.
To finish off here's a couple of bits of zany British humour featuring wasps in minor roles (you will have to listen for a couple of minutes in each case to get to the wasp reference).
Source: http://www.dailykos.com/story/2013/01/04/1176467/-Backyard-Science-Arthropod-Diversity-Part-IV
pi day monta ellis wiz khalifa taylor allderdice mixtape reggie wayne taylor allderdice vincent jackson vicki gunvalson
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