Parasitic Wasps

A very long time ago I went on the Imperial College’s Parasitic Hymenoptera course, run by Donald Quicke, Mike Fitton, Mark Shaw & Kees van Achterberg (to name but a few of the many excellent tutors). After that I came back and tried to distil some of the information they taught me into a single web-page that might be useful to others. I have moved websites since those days but I managed to find a copy of the old page and have brought it back to life. There are lots of typographic problems that need fixing but the data is basically there:

This guide is aimed at amateur entomologists or just about anyone who would like to learn more about parasitic Hymenoptera. It is a summary of things I have either read or discovered myself – so for more a more detailed study see the books in the bibliography section. Lastly, my thanks go to all those people who have helped me get started.


What are parasitic wasps?

For taxonomic purposes, parasitc wasps (parasitica for short)a are grouped together with bees, ants and other wasps in the insect order Hymenoptera. The Hymenoptera are one of the most species-rich group of insects in the world – in Great Britain alone there are approximately 7100 species (6000+ parasitica), compared with ~6500 flies or ~4000 beetles.

In general, Hymenoptera have 2 pairs of wings (but some speciesare wingless), and they develop using complete metamorphosis (egg -> larva -> pupa -> adult). Nearly all are carnivorous or insectivorous – the main exceptions being the Sawflies and gall wasps. A less obvious feature, but one that sets all Hymenoptera apart from most other insect groups, is a haplo-diploid genetic makeup. This means that only the females in any species have a full compliment of chromosomes – the males have half a set. Sex determination is is done at the point of fertilisation – fertilised eggs develop into females and unfertilised eggs develop into males. A tremendously powerful consequence of this process is that females can actually control the sex ratio of their offspring by controlling how many fertile (female) or infertile (male) eggs they lay.


Kingdom: Animalia
Phyllum: Arthropoda
Class: Hexapoda

Order: Hymenoptera

Sub-order: Apocrita


Technically speaking, ‘Parasitic Wasps’ are not actually parasites– they are parasitoids. This is because a true parasite is something that lives at the expense of its host but doesn’t actually kill it, whereas parasitoids nearly always kill their host. In general though most people still use the term ‘Parasitic Wasps’.

Parasitoid larvae usually develop by feeding on a single host -different species develop on anything from tiny aphids and insect eggs right up to large butterfly and moth larvae. They can live and feed inside the host’s body cavity (endoparasitoids) or outside the host’s body (ectoparasitoids). They can be solitary or gregarious – with anything from 1 to many 1000’s of larvae consuming the same host.

picture shows three female ichneumon wasps called Stilbops ruficornis. These wasps are searching the flowers of Field Scabious (Knautia sp.) for the eggs of a small moth (Nemophora metallica). When they find an egg they will lay their own egg inside it. The wasp’s larva will hatch in the egg but delays its development until later in the moth’s life cycle when the larva has pupated.

Fascinating life strategies

Nearly all parasitica inject venom into their host along with orjust prior to the egg. This venom is a highly complex mixture of chemicals and other agents used not just to paralyse the host, but to also modify the host’s tissues. Tissue modification is a feature of nearly all venoms, making the host more nutritious for the developing wasp larva and helping to overcome the host’s immune systems. The latter is an especially important consideration for internal parasitoids as a host’s body will usually try to surround (encapsulate) a foreign body to prevent infection and to kill any parasitoid eggs or larvae. Parasitica have developed many ways of getting around this but I think the most devious must be the use of polydnaviruses (also known as Poly-DNA-viruses) (Edson et al., 1981). These viruses are injected by some endoparasitoids with the venom and have been shown to target and disable the host’s immune system – thus protecting the developing parasitoid. Other, more basic, methods of bypassing the host’s immune system include laying the egg directly into the host’s brain (ganglion), where the immune system is unable to encapsulate it.

Whichever method the parasitoid uses to prevent encapsulation itmust also protect itself against many other dangers. One of the most serious being the possibility that a host will succumb to a fungal or bacterial infection and die before the parasitoid has finished with it. To prevent this, many larvae secrete chemicals with antibiotic or antiseptic properties as they move around the host’s body cavity. They also avoid damaging the host’s gut (a massive source of bacteria) by eating non-essential areas first, like body fat and the reproductive organs. Many species also use teratocytes – bundles of cells that emerge from the egg with the embryo. These cells absorb food from the host’s body cavity and the parasitoid larva feeds on them – removing the need for it to feed directly on the host’s tissues until it is absolutely necessary.

Polyembryony is another complex strategy employed by parasitica(Ivanova-Kasas, 1970), but this time its aim is to ensure the maximum number of offspring from the fewest number of eggs. Some species lay a single egg that continues to divide, cloning itself into many independent larvae – in extreme examples one egg can produce thousands of larvae. Some species have even been shown to produce different types of larvae from the same egg – normal larvae that feed and develop fully into adult wasps and others, which never mature into adult wasps, that act as guards to protect the others from attack by other parasitoid larvae.

Koinobionts and Idiobionts

The Koinobiont / Idiobiont theory was developed over the years by many researchers but was most completely described by Dr Mark Shaw & Dr Richard Askew (Askew & Shaw, 1986). They showed how parasitic wasps could be divided by examining their lifestyles – and this analysis yielded two main types, Koinobionts and Idiobionts.

The differences between Koinobionts and Idiobionts are listed and compared below. Each comparison is a gross generalisation in that there are quite a lot of species that differ from the norm in one or more respects, but most parasitica will fall into one or other grouping.



The host is (at most) only partially paralysedby the wasp’s venom and soon recovers. The host continues to develop and is only killed when the parasitoid reaches maturity. The host is totally paralysed by the wasp’svenom and it’s development is terminated.

(this last comparison is, more or less, the definition of each group)

Long larval development time – larval development is delayed in the early stages to allow the host to grow Short larval development period- the host is totally paralysed and the parasitoid must eat it as fast as possible
Pro-ovigenic – they produce many, small eggs that are fully developed the moment the wasp hatches Synovigenic – they produce a few, large eggs that develop sequentially over the life of the adult wasp
The host contiues to grow so, although each species specialises in a single stage, koinobionts are able to attack all stages Oviposition must take place when host is large enough to fully feed the parasitoid so later stages are prefered (fully grown larvae or pupae)
Oviposition on exposed hosts – the host is still active and able to look after itself Oviposition on concealed hosts – the host is paralysed and unable to protect itself so it would be easy prey for a predator
Endoparasitoids – they develop inside the body cavity of their hosts. Some ectoparasitoid koinobionts are known but they are quite unusual Ectoparasitoids – they develop outside the body of their hosts – sucking nutrients through the host’s skin
Host specialists. Very precise physiological adaptations to specific hosts. Lots of host modification & ways of preventing encapsulation Large host range – more species. The location of the host is more important and they often have highly developed means of locating & reaching concealed hosts
Specific venom that only works on a smallnumber of host species General venom that works on a variety ofhost species
Short adult life Longer adult life
Very little host feeding – a phenomenon where the adult female host drinks some host’s blood (haemolymph) Host feeding common – to get protein to make more eggs
Simpler sex ratio usually percentage driven Sex ratio influenced by host suitability. Males are usually smaller & will survive on smaller hosts & vice versa
Koinobionts are thought to have evolved from Idiobionts
This photo shows a tiny, parasitic, Chalcid wasp of the genus Torymus ovipositing inside a developing ‘Cherry Gall’ on the back of an Oak leaf (Quercus robur) – the wasp is standing on tip-toes with its head to the right and the ovipositor sheath to the left. The ovipositor itself has been doubled back along the body and directed down to the surface of the gall. The wasp will use the tip of the ovipositor to probe for the cell containing the gall-wasp and inject one egg into the hosts body cavity.

Gall Wasps

As I mentioned at the start of this article, not all ‘parasiticwasps’ are invertebrate parasitoids. Some, like the Gall Wasps (family Cynipidae), are true ‘parasites’ of plants. Although their host is totally different they still use similar strategies to the true parasitoids – they still inject venom with their eggs and this venom still modifies the host’s tissues. In the case of the gall-wasps the tissue modification takes the form of strangely shaped growths, called galls. These galls both protect the developing larva and provide it with nourishing food.

Gall wasps frequently fall prey to a huge array of parasites/parasitoidsand inquilines (cleptoparasites that don’t attack the host directly but steal their food). These communities are often very complex, involving layers of inter-dependency that defy the imagination. In one gall you may have: a host that made the gall (usually a Cynipid wasp); different species of inquiline eating the host’s food; and different species of parasitoid living on the host, the inquilines and themselves! The latter group (parasitoids on parasitoids) are called hyperparasitoids.

A good example of a large gall-wasp community is found in the OakMarble Gall (caused by the Cynipid wasp Andricus kollari). This community has been studied extensively and has been found to contain 17 species of wasp – one causer (Andricus kollari); 5 inquilines (Ceroptres arator, Synergus gallaepomiformis, S. pallidipennis, S. reinhardi and S. umbraculus); and 13 parasitoids (Eurytoma brunniventris, Sycophila biguttata, S. variegata, Megastigmus dorsalis, M. stigmatizans, Torymus geranii, T.auratus, Caenacis lauta, Hobbya stenonota, Mesopolobus amaenus, M. fasciiventris, M. sericeus, Eupelmus urozonus).

To even further complicate the situation, many of these wasps have two generations in a year – with each generation having a slightly different body shape. Some Cynipids produce different galls in different plants according to whether they are a winter/spring or summer/autumn brood. Also, parasitoids of these species often change the shape of their bodies accordingly – for instance, one generation may require a different length ovipositor to reach the host. This has allowed the parasitoids to follow their hosts through each different generation.

As well as having differently shaped bodies the two broods of Gallwasp may also reproduce differently. For instance it is quite common for the winter/early spring brood to be entirely female (parthenogenic) and for those females to lay unfertilized eggs that develop into normal, sexual progeny that appear in summer/autumn. Of course, as I mentioned above, wasps have a haplo-diploid genetic structure and can all produce males from unfertilised eggs but the trick is making females from unfertilised eggs. The clever stuff goes on when the chromosomes inside the nucleus of the egg replicate and pair-up to form the full compliment. Once this has been done the cell can divide as normal.

Some selected life histories

Polysphincta tuberosa (Ichneumonidae:Pimplinae) is unusual in being a koinobiont ectoparasitoid – allowing the host to continue development but living outside the host’s body. The adult lays a single egg on the front of a spider’s abdomen – the host is often the common white & yellow/green spider Araniella cucurbitina. The position of the egg makes it impossible for the spider to remove it using its legs or mandibles and makes rubbing it off very difficult. When the egg hatches the larva stays in the same position and pierces the host’s skin to drink its body fluids. In its first weeks the larva remains quite small (<=2mm) but this is because it is ticking over, waiting for the host to get big enough. Once it senses the host is the right size it will suck the spider dry over night and grow to 5-6mm in length! The larva then spins a silk cocoon and pupates – the adult hatching after a couple of weeks.

Dinocampus coccinellae (Braconidae: Euphorinae) is another koinobiont, except this is an parthenogenic endoparasitoid of adult ladybird beetles. The wasp stalks a suitable ladybird before thrusting its ovipositor between the host’s abdominal plates and laying a single egg inside. When the egg hatches the first job for the larva is to eliminate any competition. It is equipped with large, pointed mandibles and it uses these to stab other parasitoid eggs and larvae. Soon after this is will shed its skin revealing mouthparts suitable for eating the host. During development the larva takes very great care not to eat any of the ladybird’s vital organs – in fact it seems to limit itself to the ladybird’s fat store and gonads. When it is ready to pupate, it uses its mandibles to cut each of the six motor-neurones that control movement in the ladybird’s legs before breaking out of the host’s abdomen and spins a cocoon between the host’s legs. This may seem strange behaviour but the wasp actually wants the ladybird to stand sentry over the cocoon.

The ladybird can’t move but it is still alive so the bright warning colours and reflex bleeding that once protected the ladybird from predators will now protect the wasp. Eventually the wasp hatches and flies off to find another ladybird leaving the host to starve.


Hymenopteran taxonomy is a very complex subject and, although thereis plenty of professional interest in the group (for biocontrol of crop pests etc), very few amateur have ventured into the field. This is due to many reasons – partly to the sheer numbers of species, the scarcity of good keys, and the confusing and ever changing classification of Hymenoptera. For this reason I have decided not to cover anything but the basics.

The following table shows the grouping of world Hymenoptera down to family level based on a table by M.G.Fitton – with my own comments.


– the sawflies and wood-boring wasps

SUPERFAMILY Family Comments
XYELOIDEA Xyelidae probably the most primitive group of wasps
PAMPHILIOIDEA Megalodontesidae no representatives in the UK
TENTHREDINOIDEA Argidae most families have representatives around the world (except for Pergidae, which is mainly found in the southern hemisphere and does not occur in the UK)
CEPHOIDEA Cephidae stem-sawflies
SIRICOIDEA Anaxyelidae no representatives in the UK
Siricidae wood-boring wasps
ORUSSOIDEA Orussidae unusual superfamily related to Siricoidea – not recorded in the UK for 150 years


(“waisted” Hymenoptera) – parasitoid wasps & aculeates (stinging Hymenoptera)

SUPERFAMILY Family Comments
STEPHANOIDEA Stephanidae no representatives in the UK
MEGALYROIDEA Megalyridae no representatives in the UK
EVANIOIDEA Aulacidae 1 UK species – endoparasitoids of wood boring beetles & wasps (Xiphidriidae)
Evaniidae 1 UK species – cockroach egg parasitoids
Gasteruptiidae parasitoids on spechids, vespids and apids (Hymenoptera) and ‘secondary cleptoparasites’ on the food stores of their victims. This means that host is not large enough so the gasteruptiid larva continues development by eating the host’s pollen store.
CERAPHRONOIDEA Ceraphronidae little studdied group – some are endoparasitoids of cecidomyiid flies
Megaspilidae large family – ectoparasitoids of a wide range of hosts
PROCTOTRUPOIDEA Austroniidae Australian
Diapriidae endoparasitoids in the pupae of flies
Heloridae parasitoids on lacewings
Monomachidae no representatives in the UK
Peradeniidae Australian
Pelecinidae no representatives in the UK
Proctotrupidae parasitoids – mainly beetles
Renyxidae no representatives in the UK
Roproniidae no representatives in the UK
Vanhorniidae possibly 1 UK species
PLATYGASTROIDEA Platygastridae endoparasitoids on flies
Scelionidae endoparasitoids on invertebrate eggs
CYNIPOIDEA Cynipidae gall wasps
Figitidae parasitoids
Himalocynipidae parasitoids (not in the UK)
Ibaliidae a small group with 2 UK species – parasitoids on wood-boring wasps
MYMAROMMATOIDEA Mymarommatidae microscopic (~1mm) – one rare UK species
CHALCIDOIDEA Agaonidae no UK species – larvae develop in figs
Aphelinidae egg parasitoids – mainly Homoptera (a group of true bugs) but some also of other insects
Chalcididae solitary endoparasitoids of the pupae of butterflies & moths (order Lepidoptera), Diptera & Sawflies (Symphyta)
Elasmidae usually gregarious idiobiont ectoparasitoids of lepidopterous larvae and also pseudo-hyperparasitoids via Ichneumonoidea cocoons
Encyrtidae egg parasitoids
Eucharitidae parasitoids of ants
Eulophidae parasitoids on eggs and larvae
Eupelmidae parasitoids on a variety of insect orders
Eurytomidae endophytic phytophages (plant-eaters) or parasitoids on phytophages
Leucospidae no representatives in the UK
Mymaridae egg parasitoids of insect eggs – especially booklice (order Psocoptera)
Ormyridae parasitoids of gall-forming insects
Perilampidae parasitoids – 9 UK species
Pteromalidae one of the largest families with very varied life-histories
Rotoitidae New Zealand only
Signiphoridae parasitoids – have been reared from scale-insects, white-flies and the pupae of flies
Tanaostigmatidae Tropical & sub-tropical
Tetracampidae parasitoids on insects
Torymidae mainly parasitoids, especially of gall-forming insects, but some are phytophages (or both)
Trichogrammatidae egg parasitoids of insects – including thrips (order Thysanoptera)
ICHNEUMONOIDEA Braconidae ichneumon wasps – parasitic on a wide variety of invertebrates
CHRYSIDOIDEA Bethylidae predators of beetles & moth larvae – but they behave as parasitoids
Chrysididae ruby-tailed wasps – parasitoids & cleptoparasites on aculeate (stinging) Hymenoptera
Dryinidae mainly parasites on plant bugs
Embolemidae 1 UK species
Plumariidae South America & South Africa
Sclerogibbidae tropics only
Scolebythidae southern hemisphere
VESPOIDEA Bradynobaenidae no UK representatives
Eumenidae Potter or Mason wasps
Formicidae ants
Mutillidae velvet ants – cleptoparasites on the larval food-cells of bees
Pompilidae spider hunting wasps
Rhopolosomatidae rare – tropical & subtropical areas
Sapygidae 2 UK species – cleptoparasites on the larval food-cells of bees
Scoliidae endoparasitoids of subterranean beetle larvae
Sierolomorphidae North & Central America
Tiphiidae beetle parasitoids
Vespidae this group includes the common, communal wasps
APOIDEA Apidae bees
Sphecidae solitary wasps

Selected & annotated bibliography

I have chosen to split the bibliography into three sections tomake it more useful. First is a list of books I have found useful (below). The next is a breakdown of parasitica groups and the keys you need to use to identify them. Lastly is a list of references that I have quoted in the main text of this article.

    • Handbooks for the identification of British Insects:Volumes 6-8. Each volume is divided into many parts and each parthas been written by a different author. These books must formthe basis of any identification library but there are gaps andsome large groups of wasps are not covered (see below). The earliestparts were written in the 1950s and many are now out of printbut those still in print can be obtained from the Royal Entomological Society, while the others can usually be found in good entomological libraries like the British Entomological Society library at Dinton Pastures, Winnersh, Reading. In the following list parts that are out of print are listed in [italics].
      • [part 1: Introduction and keys to families. O.W. Richards,1956]
      • part 2(a): Symphyta (except Tenthredinidae). J. Quinlan& I.D. Gauld, 1981
      • [part 2(b): Symphyta (Tenthredinidae). R.B. Benson,1952]
      • [part 2(b): Symphyta (Nematinae). R.B. Benson, 1952]
      • part 3(a): Bethyloidea – Embolemidae, Bethylidae & Dryinidae.J.F. Perkins, 1976
      • part 3(b): Scolioidea, Vespoidea & Sphecoidea. O.W. Richards,1980
      • part 3(c): Formicidae. B. Bolton & C. Collingwood, 1975
      • part 4: Spider Wasps (Pompilidae). M.C. Day, 1988
      • part 5: Cuckoo-wasps (Chrysididae). D. Morgan, 1984: Theonly problems I have had are with the chapter on the genusChrysis, which according to other people I have talked todoesn’t work very well anyway – too many wasps key to C.impressa.This genus obviously needs revision.
      • part 1: Pimpline ichneumon flies (Ichneumonidae: Pimplinae).M.G. Fitton, M.R. Shaw & I.D. Gauld
      • [part 2(ai): Ichneumonidae, key to subfamilies and Ichneumoninae(1). J.F. Perkins, 1959]
      • part 2(aii): Ichneumonidae – Ichneumoninae (Ichneumonini),Alomyinae, Agriotypinae and Lycorininae. J.F. Perkins, 1960
      • [part 2(b): Ichneumonidae – Orthopelmatinae & Anomaloninae.I.D. Gauld & P.A. Mitchell, 1977]
      • part 11: Classification and Biology of Braconid Wasps.M.R. Shaw & T. Huddleston. 1991: Not strictly an identificationguide (there is a good key to UK sub-families) but it is avery good introduction to the biology of this group.
      • part 1(a): Cynipoidea – key to families & subfamilies and Cynipidae (Cynipinae). R.D. Eady & J. Quinlan, 1963: Reasonably easy to use but one or two diagrams could have been better arranged – most notably the first couplet in the sub-family Cynipinae in which the pictures are facing in opposite directions!
      • [part 1(b): Cynipoidea – Eucoilidae. J. Quinlan, 1978: Quite a good key but you need a strong microscope and lots of light.]
      • part 1(c): Cynipoidea – Charipidae, Ibialidae & Figitidae.N.D.M. Fergusson, 1986: Again, a good microscope and a lot of light are necessary. I have been struggling with Charipidae mainly because there is very little information to double-check the id. Recently I have been told that more recent authors have discovered many new species and split existing species. Therefore, until a new key has been written, I suggest non-experts should not attempt identifications.
      • [part 2(a): Chalcidoidea – Agaontidae, Leucospidae, Chalcididae, Eucharitidae, Perilampidae, Cleonymidae & Thysanidae. Ch. Ferriиre & G.J. Kerrich, 1958]
      • part 2(b): Chalcidoidea – Elasmidae & Eulophidae (Elachertinae,Eulophinae & Euderiinae). R.R. Askew, 1968
      • part 3(di): Proctotrupoidea – Diapriidae (Diapriinae). G.E.J. Nixon, 1980
      • part 3(dii): Proctotrupoidea – Diapriidae (Belytinae). G.E.J.Nixon, 1957
  • Zoologische Verhandelingen: Illustrated key to the subfamiliesof the Braconidae (Hymenoptera: Ichneumonoidae). By C. vanAchterberg, 1993. An essential and very well written key to Braconidae – one of the commonest groups. The key will only take you as far as sub-family level though – from there on you must get hold of papers & journal extracts.
  • Identifying British Insects and Arachnids (an annotated bibliographyof key works). Edited by Peter Barnard. An essential referencework for finding the most up to date papers on just about every group. Many papers on parasitica are in very obscure journals and this book can save you days of searching.
  • The Hymenopterist’s Handbook. Edited & revised CliveBetts, 1986. A very good introduction to the group with a very useful bibliography listing most of the key identification works for all the groups of Hymenoptera. If I need to identify a specimen I find the family description and this tells me the papers that cover the group. After a quick skim through the bibliography you have the exact name of the paper and can retrieve it from a good entomological library.
  • The Taxonomy & Biology of Parasitic Hymenoptera. By Mike Fitton, Donald Quicke, Kees van Achterberg, Nigel Fergusson, Lohn LaSalle, John Noyes, Andy Polaszek & Mark Shaw. Course material to the course of the same name run annually but the Natural HistoryMuseum & Imperial College (Silwood Park).
  • The Hymenoptera. Gauld & Fitton (eds). This is an excellent introduction to the Hymenoptera and provides more detailed information than I have given here. It also deals with non-parasitic groups.
  • Parasitic Wasps. By Donald L. Quicke. A very good, in-depth look at the biology of parasitic wasps. Very well written, but probably not one for the beginner.
  • Naturalist’s Handbook – Plant Galls. By M.Redfern & R.Askew. A very good introduction to all forms of plant gall (not just wasp galls) and their associated communities.
  • Rearing Parasitic Hymenoptera. By Mark Shaw. A very good guide to rearing parasitoids in captivity with a good, simple explanation of their biology.
  • Zoologische Verhandelingen: Revision of the European species of Torymus Dalman ( (Hymenoptera: Torymidae). By Vere Graham & M.J. Gijswijt. A difficult key to get in to but the only/best species-level key to the genus Torymus.
  • Hymenoptera of the world – an identification key to families.By Goulet & Huber et al. This is a very good starting point for working out which group your wasp belongs to. The key has itsfaults but it works for most things given a little patience.
  • The Oak Marble-Gall in Britain. By Robin Williams. Available from the author in a paperback, ring-bound, A4 format. A good guide to the insects that come out of Oak Marble galls. Care must be taken if trying to use this book to identify the inhabitants of other galls, as there are so many other very similar species.

Which key do I use for UK Apocrita?

The following table has been constructed using information available in Peter Barnard’s “Identifying British Insects and Arachnids” (see above). I would heartily recommend this book to anyone wishing to study British insects – my table is only a short summary of what is available and it really included here so that I can comment on each paper.


(“waisted” Hymenoptera) – parasitoid wasps & aculeates (stinging Hymenoptera)

EVANIOIDEA Crosskey, R.W. 1951. The morphology, taxonomy, and biology of the British Evanioidea (Hymenoptera).The Transactions of the Royal Entomological Society of London 102:247-301.I have only had experience with Gasteruptiidae but have found this keyvery easy to use with a high degree of confidence.
CERAPHRONOIDEA Ceraphronidae Verymessy – no single work and most keys are part of smaller papers

on various European genera.

Megaspilidae Verymessy – no single work and most keys are part of smaller papers

on various European genera.

PROCTOTRUPOIDEA Diapriidae Nixon, G.E.J. 1957. Hymenoptera, Proctotrupoidea,Diapriidae subfamily Belytinae. Handbooks for the identification of British insects 8, 3(dii): 1-107.

Nixon, G.E.J. 1980. Diapriidae (Diapriinae)

Hymenoptera, Proctotrupoidea. Handbooks for the identification of British insects 8, 3(di): 1-55.

I have found these keys quite tricky to use and haven’t run much material through them.

Heloridae Pschorn-Walcher, H. 1955. Revision der Heloridae (Hymenopt., Proctotrupoidea). Mitteilungen der Schweizerischen Entomologischen Gesellschaft 28: 233-250. Apparentlya key to all European species.
Proctotrupidae Townes, H & Townes, M. 1981. A revision of the Serphidae (Hymenoptera). Memoirs of the American Entomological Institute 32: 1-541.An up to date revision but due to Townes’ unusual nomenclature it may be difficult to use.Nixon, G.E.J. 1938. A preliminary revision of the British Proctotrupinae (Hym., Proctotrupoidea). Transactions of the Royal Entomological Society of London. 87: 431-465.

A relatively easy set of keys to use but it does have mistakes and it is now quite out of date.

King, G. “Key to the British Proctotrupidae”

– in preparation

Currently the keys are out of date and confused by Townes’ unusual nomenclature.

Geoff King’s key should bring together all known keys and provide the latest names for each species.

Vanhorniidae Hedquist, K.L. 1976. Vanhornia leileri n.sp. from central Sweden (Hymenoptera: Proctotrupoidea,Vanhorniidae). Entomologica Scandinavica 7: 315-316.An article on the one north-west european species, which is included because it might conceivably occur in Scotland.
PLATYGASTROIDEA Platygastridae Kozlov, M.A. 1971. (Proctotrupoids (Hymenoptera,Proctotrupoidea) of the USSR.) Trudy Vsesoyuznogo Entomologicheskogo

Obshchestva 54: 3-67. (In Russian.)

I haven’t seen this key.

Scelionidae Masner, L. 1980. Key to the genera of Scelionidae of the Holarctic region, with descriptions of new genera and species (Hymenoptera: Proctotrupoidea). Memoirs of the Entomological Society of Canada 113: 1-54.I haven’t seen this key.
CYNIPOIDEA Cynipidae Eady, R.D. & Quinlan, J. 1963. Hymenoptera, Cynipoidea. Key to the families and subfamiliesand Cynipinae (including galls). Handbooks for the identification of British insects. 8, 1(a): 1-81.This is a reasonably easy key to use but it is showing its age and many new species have been discovered since its publication.Williams, R. 1999. The Oak Marble Gall in Britain. Published by the author.

In addition, Robin Williams is currently updating many of the old keys and bringing them together into one volume covering the wasps of Oak gall communities.

Redfern, M. & Askew, R.R. Naturalist’s Handbook – Plant Galls.

Keys are limited but this is a very good introduction to all forms of plant gall (not just wasp galls) and their associated communities.


Figitidae Fergusson, N.D.M. 1986. Charipidae, Ibaliidae & Figitidae Hymenoptera: Cynipoidea. Handbooks for the identification of British insects 8(1c): 1-55.I have found the key to Charipidae (now Charipinae, a subfamily of Figitidae) very difficult to use with any degree of confidence and I am told the group is being reviewed – so watch this space!Quinlan, J. 1978. Hymenoptera, Cynipoidea, Eucoilidae. Handbooks for the identification of British insects 8, 1(b):1-58.

Eucoilidae has been downgraded to subfamily Eucoilinae within the family Figitidae. The key to genus is fine but I have had problems getting further with any degree of confidence.

Ibaliidae Fergusson, N.D.M. 1986. Charipidae, Ibaliidae & Figitidae Hymenoptera: Cynipoidea. Handbooks for the identification of British insects 8(1c): 1-55.
MYMAROMMATOIDEA Mymarommatidae Blood, B.N. & Kryger, J.P. 1922. A new mymarid from Brockenhurst. Entomologist’s Monthly Magazine 58:229-230A description of the only UK species. I haven’t seen this work.
CHALCIDOIDEA Aphelinidae Ferriere, C. 1965. Faune de l’Europe et du Bassin Mediterraneen. 1. Hymenoptera Aphelinidae d-Europeet du bassin mediterraneen.I haven’t seen this key.
Chalcididae Ferriere, C. & Kerrich, G.J. 1958. Hymenoptera 2. Chalcidoidea Section (a). Handbooks for the identification of British insects 8(2a): 1-40.
Elasmidae Askew, R.R. 1968. Handbooks for the identification of British insects 8 (2b): Chalcidoidea – Elasmidae & Eulophidae (Elachertinae, Eulophinae & Euderiinae).
Encyrtidae Peck, O., Boucek, Z. & Hoffer, A. 1964. Keys to the Chalcidoidea of Czechoslovakia (Insecta:Hymenoptera). Memoirs of the Entomological Society of Canada34: 1-120.This key covers Central European genera of Encyrtidae but includes superb keys to all Chalcidoidea – a really good reference work. The only problem is that I bought the last copy the ESC had in stock!
Eucharitidae Ferriere, C. & Kerrich, G.J. 1958. Hymenoptera 2. Chalcidoidea Section (a). Handbooks for the identification of British insects 8(2a): 1-40.
Eulophidae Askew, R.R. 1968. Handbooks for the identification of British insects 8 (2b): Chalcidoidea – Elasmidae & Eulophidae (Elachertinae, Eulophinae & Euderiinae).There are also works by Graham and Hansson.
Eupelmidae Very messy – no single work and most keys are part of smaller papers on various Europeangenera.
Eurytomidae Very messy – no single work and most keys are part of smaller papers on various Europeangenera.
Mymaridae Very messy – no single work and most keys are part of smaller papers on various Europeangenera.
Ormyridae Hoffmeyer, E.B. 1930-31. Beitrage zur Kenntnis der danischen Callimomiden mit Bestimmungstabellender europaischen Arten (Hym., Chalc.) (Callimomidenstudien5). Entomologiske Meddelelser 17: 232-282.Apparently this key is for Danish species but it contains all UK species.
Perilampidae Ferriere, C. & Kerrich, G.J. 1958. Hymenoptera 2. Chalcidoidea Section (a). Handbooks for the identification of British insects 8(2a): 1-40.
Pteromalidae Boucek, Zdenek & Rasplus, Jean Yves. 1991. Illustrated key to West-Palearctic Genera of Pteromalidae(Hymenoptera – Chalcidoidea).It can take ages to wade through all the couplets and get down to genus – but it works and it is relatively easy to follow.
Signiphoridae Ferriere, C. & Kerrich, G.J. 1958. Hymenoptera 2. Chalcidoidea Section (a). Handbooks for the identification of British insects 8(2a): 1-40.
Tetracampidae Peck, O., Boucek, Z. & Hoffer, A. 1964. Keys to the Chalcidoidea of Czechoslovakia (Insecta:Hymenoptera). Memoirs of the Entomological Society of Canada34: 1-120.This key apparentlycovers Central European genera. I have the book but I have never used this key.

Also, Graham, M.W.R. de V. 1969. The Pteromalidae of north-western Europe (Hymenoptera: Chalcidoidea). Bulletin of the British Museum (Natural History) (Entomology) Supplement 16: 908pp.

Still the standard work – but very difficult to use unless you are familiar with the group and have a good microscope.

Torymidae M.W.R. de Vere Graham & M.J. Gijswijt. Zoologische Verhanelingen: Revision of the European species of Torymus Dalman ( (Hymenoptera: Torymidae).A difficult key to get in to but the only/best species-level key to the genus Torymus. Unfortunately there are other common genera (like Megastigmus), which are not covered by the key.
Trichogrammatidae Peck, O., Boucek, Z. & Hoffer, A. 1964. Keys to the Chalcidoidea of Czechoslovakia (Insecta:Hymenoptera). Memoirs of the Entomological Society of Canada34: 1-120.This key covers Central European genera. I haven’t seen this key.
ICHNEUMONOIDEA Braconidae C. van Achterberg, 1993. Zoologische Verhandelingen: Illustrated key to the subfamilies of theBraconidae (Hymenoptera: Ichneumonoidae).An excellent key to sub-family level.Handbooks for the Identification of British Insects (part 11): Classification and Biology of Braconid Wasps. M.R. Shaw & T. Huddleston. 1991

As well as being a very good guide to the biology of this group tis book includes a good key to UK sub-families But to get further with either key you will have to be prepared to do some paper chasing and look for references to published keys in journals.


Ichneumonidae Goulet & Huber et al. Hymenoptera of the world – an identification key to families.A reasonable key to sub-family but there are problem areas. M.G. Fitton is writing a new key to sub-families but, at the time of writing, this is still in prep.
CHRYSIDOIDEA Bethylidae Perkins, J.F. 1976. Handbooks for the identification of British insects 6(3a): Bethyloidea – Embolemidae, Bethylidae & Dryinidae.Many of the keys are very difficult to use and contain out of date nomenclature.For instance the Dryinidae are always going to be tricky but are best covered by:

Olmi, M. 1994. The Dryinidae and Embolemidae (Hymenoptera: Chrysidoidea) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica.

Chrysididae Morgan, D. 1984. Handbooks for the identification of British insects 6 (part 5): Cuckoo-wasps(Chrysididae).The only problems I have had are with the part on the genus Chrysis, which doesn’t work very well – the genus needs considerable revision.Linsenmaier, W. 1997. Die Goldwespen der Schweiz

You have to be able to read german but it is an alternative to the traditional key (see above).

Dryinidae Olmi, M. 1994. The Embolemidae & Dryinidae (Hymenoptera: Chrysidoidea) of Fennoscandia &Denmark.This is by far the most up to date key to the group, which replaces the chapters in Perkins, 1976 (see below)Perkins, J.F. 1976. Handbooks for the identification o British insects 6(3a): Bethyloidea – Embolemidae, Bethylidae & Dryinidae.
VESPOIDEA Eumenidae Yeo, P.F. & Corbet, S.A. 1995. Naturalist’s Handbooks #3 – Solitary wasps.This is my favourite key because it is so easy to use and it is newer than Richards (see below). It does not cover one or two of the more difficult genera but these can be mopped up with Richards’s keys.Richards, O.W. 1980. Scolioidea, Vespoidea and Sphecoidea. Hymenoptera, Aculeata. Handbooks for the identification of British insects 6, 3(b): 1-118.

and the excellent new booklet:

Archer, M.E. 2000. The British Potter and Mason wasps – a handbook. Vespid Studies.

Formicidae Bolton, B. & Collingwood, C.A. 1975, Hymenoptera, Formicidae. Handbooks for the identification of British insects 6(3c): 1-34.I haven’t seen this key.Skinner, G.J. & Allen, G.W. 1996. Naturalist’s Handbooks #24 – Ants.
Mutillidae Yeo, P.F. & Corbet, S.A. 1995. Naturalist’s Handbooks #3 – Solitary wasps.(see my comments above)Richards, O.W. 1980. Scolioidea, Vespoidea and Sphecoidea. Hymenoptera, Aculeata. Handbooks for the identification of British insects 6, 3(b): 1-118.
Pompilidae Day, M.C. 1988. Handbooks for the identification of British insects 6 (part 4): SpiderWasps (Pompilidae).A very nice, up to date key. I have had no major problems with it. 
Sapygidae Yeo, P.F. & Corbet, S.A. 1995. Naturalist’s Handbooks #3 – Solitary wasps.(see my comments above)Richards, O.W. 1980. Scolioidea, Vespoidea and Sphecoidea. Hymenoptera, Aculeata. Handbooks for the identification of British insects 6, 3(b): 1-118.
Scoliidae 1 UK species in the Channel Islands
Tiphiidae Yeo, P.F. & Corbet, S.A. 1995. Naturalist’s Handbooks #3 – Solitary wasps.(see my comments above)Richards, O.W. 1980. Scolioidea, Vespoidea and Sphecoidea. Hymenoptera, Aculeata. Handbooks for the identification of British insects 6, 3(b): 1-118.
Vespidae Richards, O.W. 1980. Scolioidea, Vespoidea and Sphecoidea. Hymenoptera, Aculeata. Handbooks for the identification of British insects 6, 3(b): 1-118.Else, G. “Identification – Social Wasps”. British Wildlife Magazine volume 5, part 5 p304-311.
APOIDEA Apidae Else, G. in preparationThere are lots of George’s draft keys in circulation but many of them lack diagrams.
Sphecidae Yeo, P.F. & Corbet, S.A. 1995. Naturalist’s Handbooks #3 – Solitary wasps.(see my comments above)Richards, O.W. 1980. Scolioidea, Vespoidea and Sphecoidea. Hymenoptera, Aculeata. Handbooks for the identification of British insects 6, 3(b): 1-118.

Additional References

This section is for references to papers I have quoted from inthe above text.

  • Askew, R.R. & Shaw, M.R. (1986) Parasitoid Communities:Their size, structure and development. In Insect Parasitoids (eds. J. Waage and D. Greathead), Academic Press, London. pp.225-264.
  • Edson, K.M., Vinson, S.B., Stoltz, D.B. and Summers, M.D. (1981)Virus in a parasitoid wasp: Suppression of the cellular immuneresponse in the parasitoid’s host. Science, 211, 582-583.
  • Ivanova-Kasas, O.M. (1970) Polyembryony in insects. In Developmental Systems: Insects(eds S.J. Counce and C.H. Waddington), AcademicPress, London. pp. 243-271.

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