| Key to Families of Hymenoptera in Great
  Britain   (Derived from Borror & Delong, 1964; Borror et al., 1989;
  Clausen, 1940; Gauld & Bolton, 1988; Hill, 1923 & Richards, 1977 by E.
  F. Legner)   (Email Contacts)     [Please refer to <Guide> for additional illustrations & <Hymenoptera> for order details]        Superfamily placement may differ among specialists.         Note:  Not all illustrations are
  of species found in Great Britain:     
   
    | 1a.    Abdomen broadly attached to thorax, no
    marked constriction between 1st and 2nd
    abdominal segments; cenchri (two rounded prominences with roughened surface
    to engage fore wings when folded over abdomen) present except in Cephidae,
    in which the first abdominal tergite is centrally divided by a membranous
    slit; front tibia usually with 2 apical
    spurs; a closed anal cell often present in fore wing; larva with continuous
    gut; thoracic (except Orussus) and,
    usually, abdominal legs present .......... Symphyta ......  Symphyta (Chalastogastra)--sawflies
    & horntails (Sawflies, mostly phytophagous) <General Characteristics> 
    (see Benson, 1951 for key to families).  |    
   
    | 1b.    Abdomen deeply
    constricted between 1st segment (propodeum) and 2nd (first
    abdominal) except in a few minute Chalcidoidea with very reduced wing
    venation; cenchri never present and first abdominal tergite never with a
    membranous slit extending to its base; fore tibia with only one apical spur
    with 2 in the Ceraphronoidea; fore wing with no closed anal cell;
    larva with rectum not connected to front part of gut before pupation
    (except sometimes in last instar); legs absent..... Apocrita..... Apocrita Aculeata
    (stinging Hymenoptera)   
    [Characteristics] |    
   
    | 2a.    Antennae with 3 segments
    of normal thickness, 3rd very
    long and made up of several fused, followed by a thread-like flagellum of
    at least 9 segments; head without hypostomal bridge; fore wing with Rs
    forked (always in British species); male genitalia inverted (=
    strophandrious) [in British species, normal (= orthandrious) in some American
    species], parameres with cupped disks and with articulation to parameral
    plates,,,,,, (Xyeloidea) ........ Xyelidae     (Details) |    
   
    | 2b.    Antennae not as previously described, Rs
    in fore wing not forked |    
   
    | 3a.    Antennae with 11 or more
    segments except in Orussidae &&, in
    which segment 9 is swollen and longer than any of the others; head with
    hypostomal bridge; male genitalia normal.................. |    
   
    | 3b.    Antennae with 10 segments
    or less except in Diprionidae, which have antennae serrate or comb-like (Athalia, Fenella and Heteranthrus,
    Tenthredinidae, may have 10-15 antennal
    segments but lack the following characters which are found in some or all
    families under couplet 4:  pronotum with hind margin straight,
    insect >11.0 mm. long, fore tibia with 1 (not 2) apical
    spur, antennae inserted below the eyes and apparent clypeus).  Head without hypostomal bridge (the Cimbicidae,
    in which a bridge-like condition may appear to be present, have capitate
    antennae); male genitalia inverted, parameres without cupping disks
    ............. (Tenthredinoidea)   <Overview>;
    <Adults>   (Details) |    
   
    | 4a.    Antennae not inserted on ventral side
    of head; cenchri present; in genitalia of %%, the
    parameres with cupping disks and articulate to parameral plates |    
   
    | 4b.    Either antennae inserted ventrally
    beneath eyes and below the apparent clypeus (Orussoidea) or cenchri absent
    (Cephoidea); in  genitalia,
    parameres without cupping disks and not articulate but fused to parameral
    plates |    
   
    | 5a.    Pronotum with hind margin almost
    straight, the emargination being no deeper than the length of tegula;
    abdomen strongly flattened dorso-ventrally .............. (Megalodontoidea) |    
   
    | 5b.    Pronotum with hind margin deeply
    emarginate, more deeply than length of tegula; abdomen cylindrical
    ............... (Siricoidea)   (Details) |    
   
    | 6a.    Antennae flabellate; fore wing without
    separate Sc; 2nd abdominal tergite not medially
    divided (uncertain British group) ............. (Megalodontoidea)    (Details) |    
   
    | 6b.    Antennae setaceous; fore wing with
    separate Sc; 2nd abdominal tergite divided medially
    (Megalodontoidea)  Pamphiliidae   (Details) |    
   
    | 7a.    Fore wing with 1st
    abscissa of Rs directed towards base of wing, last abscissa
    recurved; mesoscutum much longer than scutellum; tegula minute, hidden;
    neck short .............. (Siricoidea) 
    Siricidae
       (Details) |    
   
    | 7b.    Fore wing with 1st
    abscissa of Rs directed towards apex of wing, last abscissa not
    recurved; mesoscutum hardly longer than scutellum with axillae; tegula normal
    though rather small; neck long .............  (Siricoidea)   (Details)   Xiphydriidae |    
   
    | 8a.   Antennae with 11 linear
    segments in %; 10 segments in &, with 9th large
    and 10th very small; no constriction between 1st and 2nd
    abdominal segments; fore wing with no enclosed anal cell; hind wing without
    cross-veins r-m or m-cu (uncertain British group)
    .............. (Orussoidea)  Orussidae   <Overview>;
    <Adults> & <Juveniles>   (Details) |    
   
    | 8b.    Antennae with 16-30
    segments, filiform or slightly clavate; slight constriction between 1st and 2nd abdominal
    segments; fore wing with closed anal cell; hind wing with cross veins r-m
    and m-cu present ............... (Cephoidea)  Cephidae   (Details) |    
   
    | 9a.    Antennae with 3
    segments, 3rd very long; fore wing with cross vein 2r absent
    .............. (Tenthredinoidea)  Argidae   (Details) |    
   
    | 9b.    Antennae with 4
    segments, 3rd very long, 4th
    minute; fore wing with cross vein 2r present,
    cell IM of a peculiar pear shape 
    .............. (Tenthredinoidea) 
    <Overview>; <Adults>     Blasticotomidae |    
   
    | 9c.    Antennae with 4-5 segments
    followed by a very strongly marked club which may show traces of
    segmentation; sides of abdomen carinate; fore wing with cross vein 2r present
    .......... Tenthredinoidea)  Cimbicidae   (Details) |    
   
    | 9d.    Antennae typically with 9
    segments, rarely with as few as 7 or with 10-15; sides of
    abdomen not carinate; fore wing often with cross vein 2r present
    ........... .(Tenthredinoidea)  Tenthredinidae   <Overview>;
    <Adults>    (Details) |    
   
    | 9e.    Antennae with 13 or more
    segments, serrate in &,
    comb-like in %; fore wing with cross vein 2r absent
    ............ (Tenthredinoidea)  Diprionidae   (Details) |    
   
    | 10a.    Wings fully developed |    
   
    | 10b.    Wings very much reduced or absent |    
   
    | 11a.    Hind wings without anal or vannal
    lobe, except in Evaniidae, in which the abdomen is attached at the top of
    the propodeum, in most Braconidae, Microgasterinae, in which antennae have 18 segments
    and some Proctotrupidae, in which the fore wing venation is characteristic;
    costa of hind wing not or imperfectly developed except (apparently) in some
    Evanioidea and Proctotrupoidea; hind femur with a trochantellus (= an
    apparent 2nd segment to trochanter which is part of femur) except in some
    Cynipoids, Chalcidoids and Proctotrupoids; last visible tergite and
    sternite of & not apposed except in Proctotrupoidea, some
    Cynipoidea and, less distinctly, Trigonaloidea; ovipositor, which is often
    elongated, is partly exposed, at least in ventral view, except in Evaniidae,
    most Cynipoidea and most Proctotrupoidea; in the Trigonalidae the
    ovipositor is reduced; tergite 8 fully
    exposed and resembling 7 except
    in a few Braconidae and Proctotrupoidea ............ Apocrita -- Parasitica   (Details) |    
   
    | 11b.    Hind wing with an anal or vannal lobe,
    except in Formicidae, in which the segment of the abdomen formes a scale or
    node and in % Mutillidae which have a felt line  on the 2nd
    abdominal tergite and in the Vespinae; the lobe is defined only by a small
    excision in the Chrysididae and Cleptidae; costal vein of hind wing often
    developed; hind femur without a trochantellus though in a few groups the
    base of femur may be ringed by a sulcus; last visible tergite and sternite
    of & apposed, except in Ceropales
    (Pompilidae) and a few parasitic bees (e.g., Melecta);
    ovipositor (sting) entirely hidden, tergite 8
    retracted and partly desclerotized (except Dryinidae); antennae with 13 segments
    or less .............. Apocrita-- Aculeata    (Details) |    
   
    | 12a.    Abdomen attached near top of
    propodeum; fore wing with costal cell wide, pterostigma present; hind wing
    with a strong vein along its fore margin and with no enclosed cells
    (sometimes one such cell in non-British species); abdomen with spiracles on
    segments 1 & 8, pygostyles present; antennae
    with 13-14 segments ............. (Evanioidea)   <Overview>   (Details) |    
   
    | 12b.    Abdomen normally attached near bottom
    of propodeum (if attached about 1/2 way up
    the propodeum (= Cenocaelius and Paxylomma of
    Braconidae), the costal cell in fore wing is obliterated  |    
   
    | 13a.    Fore wing with pterostigma and
    antennae usually with more than 16
    segments, scape short (except Streblocera).  Hind wing with at least 2 enclosed
    cells except Neorhacodes
    (Ichneumonidae, Fig. A) and some Braconidae, which have the costa and
    radius fused in fore wing up to the pterostigma and sometimes ca. 20 antennal
    segments or (Paxylomma) the
    first 2 segments of abdomen much longer than broad and the hind
    basitarsus thickened; trochantellus distinct, at least on hind leg;
    spiracles on abdominal segments 1-8, or Braconidae, Sigalphinae (Chelonus, etc.) 1-6;
    pygostyles present |    
   
    | 13b.    Antennae with not more than 16 segments;
    fore wing with no true pterostigma except in Heloridae and Proctotrupidae,
    in which the costal cell is wide, and the Ceraphronidae, in which the
    axillae are on the same level as the central part of the scutellum;
    venation generally reduced; hind wing with no enclosed cells except in some
    Diapriidae and Ibaliidae, in which either the head is greatly produced
    forwards or the costal cell of the fore wing is wide; trochantellus often
    indistinct or absent; in && tergites
    9 & 10 indistinguishably fused, except
    in some Proctotrupidae
    and Ceraphronidae |    
   
    | 14a.    Fore wing  with costal cell wide, Rs + M complete and cross veins
    3r-m, 2r-m, Rs
    and 2m-cu present; tarsi with
    plantar lobes; last visible tergite and sternite almost apposed, ovipositor
    reduced and hidden, abdominal tergite 9 in &&
    retracted with the central part membranous; tergite 10 not
    separately developed; mandibles with 4 large
    teeth on the right, 3 on the left one; antennae with
    more than 20 segments in the one British species)  ........... (Trigonaloidea) 
    Trigonalidae   <Habits>;
    <Adults> & <Juveniles>   (Details) |    
   
    | 14b.    Fore wing with costal cell almost or
    quite obliterated, at least one of cross-veins 3r-m, 2r-m, Rs
    and 2m-cu absent; tarsi without
    plantar lobes; last visible tergite and sternite of & abdomen
    not clearly apposed, ovipositor usually clearly exserted and abdominal
    tergite 9 often not retracted .............. (Ichneumonoidea)   <Overview>   (Details) |    
   
    | 15a.    Either fore wing with well-developed
    costa or the edge of abdomen sharp and curved downwards, or head much produced
    forwards and antennae inserted on shelf-like process; pronotum either
    obtuse below but with a narrow posteroventral process which meets its
    opposite from the other side beneath the fore coxae, or pronotum is fully
    coadapted to mesepisternum; abdomen rarely compressed, spiracles on
    abdominal segments 1, 1 & 8, or 1-6; last
    visible tergite and sternite of & apposed,
    pygostyles present; ovipositor hidden except in Proctotrupidae, in which it
    projects inside the enlarged pygostyles; antennal scape usually long, if
    short then a pterostigma present ............. (Proctotrupoidea)   <Overview>   (Details) |    
   
    | 15b.    Fore wing with no pterostigma;
    proximal part of costa not developed, except weakly in Ibaliidae, which
    have a short antennal scape; abdomen with spiracles on segments 1 & 8, last
    visible tergite and sternite of & not
    apposed; ovipositor exposed, at least below, except in most Cynipoidea in
    which abdomen is usually compressed laterally |    
   
    | 16a.    Pronotum lateroventrally pointed and
    closely coadapted to mesepisternum, posteriorly extending back to tegulae;
    fore wing with cell R-1 mostly
    complete; antennae with scape short and with 12-16 segments;
    trochantellus usually not developed; abdomen in & with
    tergite 9 retracted and desclerotized; abdomen usually compressed
    laterally, pygostyles absent ............. (Cynipoidea)    <Overview>   (Details)   [See Subfamilies] |    
   
    | 16b.    Pronotum lateroventrally rounded, not
    closely coadapted to mesepisternum, posteriorly usually distinctly
    separated from tegulae; fore wing with cell R-1 not
    defined by proper veins or absent; antennal scape usually long (not clearly
    so in some Mymaridae); antennae with 13 segments
    or less; trochantellus often present; abdomen rarely compressed, with
    pygostyles in & central portion of tergite 9 exposed
    and pigmented .......... (Chalcidoidea)   <Overview>    (Details) |    
   
    | 17a.    Hind wing with anal lobe; fore wing
    not longitudinally folded, cross vein 2m-cu and 2r-m absent; antennae
    inserted well above clypeus, with 13
    segments; abdomen  short,
    compressed, with a long, abrupt petiole and a short, often hidden,
    ovipositor; propleura not meeting dorsally and forming a neck ............
    (Evanioidea)  Evaniidae   <Habits>;
    <Adults> & <Juveniles>   (Details) |    
   
    | 17b.    Hind wing with no anal lobe; antennae
    with 13 segments in %, 14 in &; abdomen
    long, gradually clavate, ovipositor exserted, often long; propleura meeting
    above and forming a neck |    
   
    | 18a.    Fore wing not longitudinally folded,
    with cross veins 2m-cu and 2r-m present;
    antennae inserted just above clypeus ............... (Evanioidea)  Aulacidae  <Habits>;
    <Adults>   (Details) |      
   
    | 19a.    Fore wing  with cross vein 2m-cu almost
    invariably present; Rs+M interrupted; hind wing with cross vein r-m
    meeting Rs after that vein leaves Sc+R (including Agriotypus and Neorhacodes; the
    latter would key to the Braconidae but the fore wing  is characteristic) ...............
    (Ichneumonoidea)  Ichneumonidae   <Habits>; <Adults-1> &
    <Adults-2> & <Adults-3>; &
    <Juveniles> |    
   
    | 19b.    Fore wing  without cross vein 2m-cu; hind
    wing  with cross vein r-m
    meeting Sc+R before the separation of Rs (includes Alysiinae,
    Aphidiinae and Paxylommatinae) .......... (Ichneumonoidea)  Braconidae   <Habits>;
    <Adults-1> & <Adults-2> &
    <Adults-3> |    
   
    | 20a.    Sides of abdomen acute or distinctly
    margined; antennae with not more than 12 segments;
    front tibia with one spur ........... (Proctotrupoidea)  Scelionidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 20b.    Sides of abdomen rounded of if, in
    some Belytinae, more acute, the antennae have 14-15 segments |      
   
    | 21b.    Antennae with 11 or 12
    segments, or with 7-8 and an
    unsegmented club; if with 10, stigmal
    vein present ........... (Proctotrupoidea) 
    Scelionidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 22a.    Fore tibia with 2 spurs;
    antennae inserted very low down, at clypeal margin, with 9-11
    segments, scape very long; radial cell in fore wing not enclosed,
    pterostigma sometimes developed; scutellum usually with a frenum and with
    axillae in same plane as main surface ............... (Ceraphronoidea)   <Overivew>   (Details) |    
   
    | 22b.    Front tibia with one spur; antennae
    inserted near middle of face, with 11-15
    segments, scape usually short; radial cell in fore wing normally closed;
    scutellum without a frenum and axillae not in same plane as main surface
    ............. (Proctotrupoidea)   <Overview>    (Details) |    
   
    | 23a.    Tibial spurs 2, 1, 2; all spurs
    comb-like; large one of fore tibia not 2-forked;
    antennae with 9-10 segments in && and 10-11 in %%;
    abdominal petiole visible as a short ring, tergite 6 with
    oval patch of dense reticulation ............. (Ceraphronoidea)  Ceraphronidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 23b.    Tibial spurs 2, 2, 2; the
    large, comb-like one of fore tibia, forked; antennae with 11 segments
    in both sexes; abdominal petiole shorter, usually hidden by the next
    segment, tergite 6 without a patch of dense
    reticulation ............. (Ceraphronoidea)  Megaspilidae   <Habits>;
    <Adults>  |    
   
    | 24a.    Fore wing  with no true pterostigma, though the parastigma is sometimes
    thickened or else the abdomen is long petiolate; antennae with 11-15 segments
    inserted  far above clypeus on a
    frontal shelf or strong prominence [except in Ismarus in which
    they are inserted normally at about the middle of face, but this genus has
    venation of forewing much as in Fig. A and an enclosed cell in the hind
    wing] ............. (Proctotrupoidea) 
    Diapriidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 24b.    Fore wing with a pterostigma; antennae
    not inserted on a frontal shelf, usually nearer clypeus or at middle of
    face |      
   
    | 25b.    Antennae with 13
    segments, inserted at middle of face, scape short; fore wing with a closed,
    normally very small, radial cell; ovipositor long ...........
    (Proctotrupoidea)  Proctotrupidae   (= Serphidae) <Habits>;
    <Adults> & <Juveniles> |    
   
    | 26a.    Larger species, cell R-1 closed in
    fore wing and 9X as long as broad; hind basitarsus 2X as long
    as remaining segments together; largest segment of abdomen one of 4-6, two or
    more small tergal plates preceding the large one .........
    (Cynipoidea)  Ibaliidae   <Habits>;
    <Adults>  |    
   
    | 26b.    Smaller species, cell R-1 not
    always fully closed, less elongated; hind basitarsus normal; largest
    segment of abdomen 2 or 3, or
    these fused, at most one small tergal plate preceding the large one |    
   
    | 27a.    Rs+M, when present in fore wing,
    directed towards M+Cu rather than Sc+R; if the 2nd or 3rd
    tergites are long and form half the abdomen, the scutellum has an apical
    cup-like depression; abdomen sometimes long petiolate (Includes Eucoilinae
    & Anacharitinae) ............... (Cynipoidea)  Figitidae   <Habits>;
    <Adults>  |    
   
    | 27b.    Rs+M, when present in fore
    wing, directed towards the mid point between M+Cu and Sc+R; 2nd or 2nd & 3rd
    tergites usually the largest and forming 1/2 of
    abdomen, which is never long petiolate 
    (includes Charipinae)............ (Cynipoidea)  Cynipidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 28a.    Hind wings linear, base forming a
    stalk, wings with long fringes; ovipositor sometimes issuing almost at tip
    of abdomen; antennae without annelli (includes Mymaromminae) ............
    (Chalcidoidea)  Mymaridae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 28b.    Not as previously described |    
   
    | 29a.    Axillae advanced strongly in front of
    anterior margin of scutellum and usually in front of tegulae; tarsi usually
    with 3-4 segments |    
   
    | 29b.    Axillae not or little advanced in
    front of anterior margin of scutellum; tarsi with 5
    segments. |    
   
    | 30a.    Hind coxa much enlarged, hind femur
    compressed; tarsi with 4
    segments; marginal wing vein long. ............. (Chalcidoidea)  Elasmidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 30b.    Hind coxa not enlarged |      
   
    | 31b.    Mid coxa lying well behind the mid
    line of mesopleuron, with no groove on the underside of the thorax |    
   
    | 32a.    Tarsi usually with 4 segments
    but with 5 in most Aphelininae and a few females of other groups; fore
    wing narrower, pubescence not in rows or lines ............
    (Chalcidoidea)  Eulophidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 32b.    Tarsi with 3
    segments; fore wing very broad, pubescence usually in rows or lines, marginal
    and stigmal veins forming a single curve ........... (Chalcidoidea)  Trichogrammatidae   <Habits>;
    <Adults> & <Juveniiles> |    
   
    | 33a.    Mesepisternum little sculptured, large
    and almost completely covering the mesepimeron  (except in some %
    Eupelmidae); mid tibial spur usually enlarged  (spur enlarged in the above % which
    have a short pronotum) |    
   
    | 33b.    Mesepisternum not enlarged, of about
    the same width as the mesepimeron; mid tibial spur rarely longer than the
    bigger hind tibial one (except in some Cleonyminae which have a long
    pronotum) |    
   
    | 34a.    Mesonotum in && with
    center of scutum depressed or flat, notauli (= two grooves emanating from front
    margin of scutum) impressed at least anteriorly and usually long; males
    with scutum usually convex and notauli often much shorter but in them the
    mesepisternum is not enlarged; marginal vein of fore wing long
    .............. (Chalcidoidea)  Eupelmidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 34b.    Mesoscutum somewhat convex, notauli not more than feebly
    indicated; mesepimeron enlarged; marginal vein in fore wing as long as
    submarginal; scutellum transversely linear; mid tibia with long bristles
    ............. (Chalcidoidea)  Encyrtidae & Signiphoridae (=
    Thysanidae)  |    
   
    | 35a.    Mandibles sickle-shaped, usually with 1-2 inner teeth;
    thorax very convex, scutellum usually produced backwards; abdomen
    compressed, usually with a long petiole (uncertain British group)
    ............ (Chalcidoidea)  Eucharitidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 35b.    Mandibles stout, with 3-4 teeth at
    apex; thorax rarely convex |    
   
    | 36a.    Hind coxa large, 2-3X longer
    than front one |    
   
    | 36b.    Hind coxa not so conspicuously longer
    than front one |      
   
    | 37b.    Hind femur with at most one tooth
    beneath |    
   
    | 38a.    Notauli present; abdomen not coarsely punctured,
    ovipositor usually long and exserted ........... (Chalcidoidea)  Torymidae  (except Megastigminae)   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 38b.    Notauli very faint or absent; abdomen usually
    with rows of coarse punctures, ovipositor short .............
    (Chalcidoidea)  Ormyridae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 39a.    Pronotum short, transversely linear,
    or elongated but much narrowed in front; mesoscutum usually reticulate; usually
    metallic insects (including Miscogasterinae, Spalangiinae and Cleonyminae;
    the elongated pronotum and flattened dorsal side of abdomen in the last
    named subfamily are sometimes regarded as family characters) .............
    Chalcidoidea)  Pteromalidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 39b.    Pronotum wide, quadrate, scarcely
    narrower than mesoscutum, which is often coarsely punctured |    
   
    | 40a.    Stigmal vein thickened into a very
    large knob, if not thickened, still with ovipositor elongated; otherwise
    rather like Eurytomidae ............. (Chalcidoidea)  Torymidae  (Megastigminae)   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 40b.    Stigmal vein not so thickened;
    ovipositor short |    
   
    | 41a.    Abdomen in %% long
    petiolate and antennae somewhat verticillate; abdomen in && rounded
    or ovate, somewhat compressed, 2nd
    tergite never very large, last sternite usually produced; black or
    yellowish insects .............. (Chalcidoidea)  Eurytomidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 41b.    Abdomen small,
    subtriangular, short petiolate, 2nd or
    fused 2nd and 3rd tergites covering most of its
    surface; antennae not verticillate; thorax large but short; somewhat
    metallic insects  ...........
    (Chalcidoidea)  Perilampidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 42a.    Hind wings with no cells enclosed by
    veins; pronotum obtuse below and not closely coadapted to mesepisternum;
    abdominal spiracles on segments 1-7 or 1-8
    (Dryinidae); both sexes have same number of antennal segments
    ..............  Chrysidoidea (= Bethyloidea)   <Overview>   (Details) |    
   
    | 42b.    Hind wing with one or more cells
    enclosed by veins; abdominal spiracles on segments 1-8; nearly
    always more antennal segments in than in previous |    
   
    | 43a.    Hind wing without an anal lobe and
    first segment of abdomen forming a scale or node, or the first 2 segments
    nodiform and the 2nd segment deeply separated from
    the third both above and below ............  Vespoidea (= Formicoidea)  Formicidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 43b.    Hind wings with an anal lobe except in
    Mutillidae, in which there is a felt line 
    at the side of the 2nd
    abdominal segment; 1st segment of abdomen not
    scale-like; if nodiform, then the next segment is closely co adapted to the
    3rd |    
   
    | 44a.    Pronotum produced back to or almost to
    the tegulae with no conspicuous lobe concealing the anterior thoracic
    spiracle |    
   
    | 44b.    Pronotum not produced back to the
    tegulae but usually forming at a lower level a conspicuous lobe over the anterior
    thoracic spiracle |    
   
    | 45a.    Fore wing  usually (always in British species) longitudinally folded in
    repose, cell M+Rs+M long, longer than cell M; glossa and paraglossa
    ending in pigmented pads; eyes emarginate .......... (Vespoidea)   <Overview>   (Details) |    
   
    | 45b.    Fore wing not longitudinally folded in
    repose, cell M+Rs+M shorter; glossa and paraglossa without pads;
    eyes usually not emarginate |    
   
    | 46a.    Mandibles long, crossing one another when
    at rest; mid tibia with one spur; tarsal claws 2-forked;
    hind wing with an anal lobe; solitary species .............
    (Vespoidea)  Eumenidae   <Habits>; <Adults>
    & <Juveniles> |    
   
    | 46b.    Mandibles short
    and broad, lying transversely, one above the other; mid tibia with 2 spurs; tarsal
    claws simple; hind wing (in Vespinae) with no anal lobe; social species
    ........... (Vespoidea)  Vespidae   <Habits>; <Adults>
    & <Juveniles>  |    
   
    | 47a.    Mesopleuron divided obliquely by a
    suture running from near upper posterior corner, downwards and forwards; pronotum
    obtuse below and loosely overlapping mesopleuron; legs long, hind femur
    especially so .......... (Pompiloidea) 
    Pompilidae   (= Psammocharidae) <Habits>;
    <Adults> & <Juveniles> |    
   
    | 47b.    Mesopleuron not so
    divided; pronotum usually acute below (not in Tiphia) and coadapted
    to mesopleuron; legs usually short and stout ............ (Scolioidea)  <Overview>]
    [formerly (Pompiloidea) <Overview>]    |      
   
    | 48b.    Pubescence, at least in part (e.g.,
    near anterior thoracic spiracles), plumose or branched; hind tarsi usually somewhat
    widened and often densely pubescent ............ (Apoidea)   <Overview>   (Details) |    
   
    | 49a.    Antennae with 10 segments |    
   
    | 49b.    Antennae with 12-13 segments |    
   
    | 50a.    Antennae not inserted on a prominence
    but near to dorsal margin of clypeus; female with chelate fore tarsi  (except Aphelopus),
    sometimes apterous or brachypterous ........... (Bethyloidea)  Dryinidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 50b.    Antennae inserted on a prominence high
    above clypeus; female apterous; male winged with relatively complete
    venation ............ (Bethyloidea) 
    Embolemidae   <Habits>;
    <Adults>  |    
   
    | 51a.    Abdomen with 7 exposed
    segments; rarely metallic insects (in Britain); pronotum usually parallel-sided;
    head somewhat prognathous ............ (Bethyloidea)  Bethylidae   <Habits>;
    <Adults> & <Juveniles>
     |    
   
    | 51b.    Abdomen with 3-5 exposed
    segments; largely metallic insects (always in British species); head
    orthognathous; antennae with 13 segments |    
   
    | 52a.    Abdomen with 3 exposed
    segments, venter concave; pronotum short but wide; propodeum normally with
    sharp lateral keels or teeth; sculpture usually coarse .............
    (Bethyloidea)  Chrysididae  (Chrysidinae)   <Habits>; <Adults> & <Juveniles> |    
   
    | 52b.    Abdomen with 4-5 exposed segments,
    venter slightly convex; pronotum elongated, somewhat narrowed anteriorly;
    sculpture finer; not metallic insects 
    ........... (Bethyloidea)  Chrysididae  (Cleptinae)   <Habits>; <Adults> & <Juveniles> |    
   
    | 53a.    Second abdominal tergite with lateral
    felt lines; female apterous; male hind wing without anal lobe (forewing in
    Fig. B); body usually well punctured and with conspicuous patches of
    pubescence ............ (Tiphioidea) [Now in Vespoidea] Mutillidae 
    (= now in Sapygidae  <Habits>; <Adults> & <Juveniles> |    
   
    | 53b.    Second abdominal tergite without lateral
    felt lines; male hind wings with an anal lobe and body often smooth,
    shining and nearly bare |    
   
    | 54a.    First and 2nd
    abdominal tergites not separated by a constriction, 1st and 2nd
    sternites with only a feeble constriction between them; mesosternum simple;
    female winged ............ (Tiphioidea)  
    [Now in Vespoidea]  Sapygidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 54b.    First and 2nd
    abdominal segments separated by a deep constriction  and/or the mesosternum with 2 laminae which
    overlie or project between the bases of the mid coxae; female often
    apterous (includes Methochinae & Myrmosinae) .............
    (Tiphioidea)   [Now in Vespoidea] Tiphiidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 55a.    Antennal socket connected with
    fronto-clypeal suture by 2 sutures;
    glossa acute, labial palpi with segments equal or the first alone, elongated
    and flattened; mid coxa externally much shorter than distance from its
    summit to posterior wing base (as in Fig. B); females and many males with a
    pygidial area ............. (Apoidea) 
    Andrenidae   <Habits>;
    <Adults>  |    
   
    | 55b.    Antennal socket connected with fronto-clypeal
    suture by a single suture; labial palpi variable but rarely with first
    segment alone elongated |    
   
    | 56a.    Fore wing with first sector of M
    curved; labial mentum and submentum virtually absent; labial palpi usually with
    all segments similar; mesepisternum usually with a complete anterior
    oblique suture; metanotum horizontal; mid coxa externally much shorter than
    distance from its summit to posterior wing base ......... (Apoidea)  Halictidae   <Habits>;
    <Adults>  |    
   
    | 56b.    Fore wing with first sector of M
    straight; labial mentum and submentum present |    
   
    | 57a.    Glossa bilobed; labial submentum
    elongated, not -V-shaped; anterior oblique suture present on mesepisternum;
    mid coxa externally much shorter than distance from its summit to posterior
    wing base  .............
    (Apoidea)  Colletidae   (= Hylaeidae)  <Habits>;
    <Adults>  |    
   
    | 57b.    Glossa acute, often elongated; labial
    submentum V-shaped; anterior oblique suture very rarely complete, usually
    absent |    
   
    | 58a.    Labial palpi with segments similar and
    cylindrical; galea short; mid coxa, except in Macropis, much shorter
    than distance from its summit to posterior wing base ...........
    (Apoidea)  Melittidae   <Habits>;
    <Adults>  |    
   
    | 58b.    Labial palpi with first two segments
    elongated and sheathing; galea very elongate; mid coxa, except in a few
    parasitic Apidae, 2/3rds as
    long as distance from its summit to posterior wing base  |    
   
    | 59a.    Labrum longer than broad and widened
    to a broad articulation with clypeus; subantennal suture at outer edge of socket;
    fore wing with two submarginal cells, usually of about the same length;
    last abdominal tergite nearly always without a pygidial area; scopa (=
    dense brush of hairs), when present, on abdominal sternites ............
    (Apoidea)  Megachilidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 59b.    Labrum usually broader than long; if
    not, narrowed basally to a short articulation with clypeus; subantennal
    suture at inner edge of socket; fore wing usually with 3, rarely
    with 2 or 2 submarginal cells; if 2, the
    second is usually much shorter than first; pygidial area often present;
    scopa, when present, on hind legs, rarely also on abdominal sternites |    
   
    | 60a.    Scopa of female forming a pollen
    basket on the hind tibia and inner apical margin of tibia with a comb
    (except in Psithyrus); pygidial plate absent; social species .............
    (Apoidea)  Apidae   <Habits>; <Adults>
    & <Juveniles> |    
   
    | 60b.    Scopa of female not forming a pollen
    basket on the hind tibia which has no apical comb |    
   
    | 61a.    Pygidial plate nearly always present
    in && and usually in %%; clypeus
    protruberant, lateral portions seen from below bent posteriorly and lying parallel
    to long axis; fore coxa a little broader than long ............
    (Apoidea)  Anthophoridae   (= Nomadidae) <Habits>;  <Adults>
     |    
   
    | 61b.    Pygidial plate
    absent; clypeus not protruberant, lateral portions seen from beneath
    transverse rather than longitudinal; fore coxa transverse .......
    (Apoidea)  Anthophoridae (=
    Xylocopidae)   (= Nomadidae) <Habits>;  <Adults>
     |    
   
    | 62a.    Abdominal sternites very membranous,
    tending to dry into a longitudinal fold; antennae often multiarticulate |    
   
    | 62b.    Abdominal sternites fully sclerotized |    
   
    | 63a.    Abdomen with tergites 2 & 3 fused, not
    overlapping, its petiole usually broad, if narrow then its dorsal surface
    is straight in profile (either a circular space between clypeus and
    mandible, as in Fig. A, or mandibles exodont as in Fig. B); tegulae present
    .... (Ichneumonoidea)  Braconidae   <Habits>;
    <Adults-1> & <Adults-2> &
    <Adults-3>  &  <Juveniles> |    
   
    | 63b.    Abdomen with
    tergites 2 & 3 usually separate and
    overlapping; if fused, the abdomen is long petiolate and the dorsal surface
    of the petiole is curved in profile; no circular space between clypeus and
    mandibles, latter not exodont; tegulae often absent .......
    (Ichneumonoidea)  Ichneumonidae   <Habits>; <Adults-1> &
    <Adults-2> & Adults-3>; & <Juveniles> |    
   
    | 64a.    First or 1st and 2nd segments
    of abdomen scale-like or nodiform, distinctly separated from posterior part
    of abdomen .............. (Formicoidea) 
    Formicidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 64b.    Abdominal petiole not scale-like nor
    composed of 2 nodiform segments |    
   
    | 65a.    Head pear-shaped, long axis vertical,
    the 10-segmented antennae, which are as long as whole body, arise
    from a prominence; abdomen not long petiolate; females ...........
    (Bethyloidea)  Embolemidae   <Habits>;
    <Adults>  |    
   
    | 65b.    Head formed differently or otherwise
    not as previous |    
   
    | 66a.    Pronotum does not extend back to the
    tegulae; tegulae absent in some Trichogrammatidae, but these have only 3 tarsal
    segments; pronotum not coadapted to the mesepisternum which has a distinct
    postspiracular sclerite ......... (Chalcidoidea)   <Overview>   (Details) |    
   
    | 66b.    Pronotum extends back to tegulae if
    these are present; tarsi always with 5 segments;
    postspiracular sclerite not distinctly developed |    
   
    | 67a.    Antennae with 10 segments
    or less |    
   
    | 67b.    Antennae with >10 segments |    
   
    | 68a.    Females with chelate fore tarsi  and 10 antennal
    segments; pronotum not coadapted to mesepisternum .............
    (Bethyloidea)  Dryinidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 68b.    Fore tarsi not chelate; pronotum
    somewhat distinctly coadapted to mesosternum |    
   
    | 69a.    Abdomen compressed laterally,
    conspicuously deeper than broad, integument (except for base) mostly smooth
    and shining ........ (Cynipoidea)   <Overview>   (Details) |    
   
    | 69b.    Abdomen not compressed laterally;
    integument often more sculptured and pubescent |    
   
    | 70a.    Head somewhat markedly longer than broad,
    usually clearly prognathous; thoracic sutures usually more complete
    ............. Chrysidoidea (= Bethyloidea) 
    Bethylidae   <Habits>;
    <Adults> & <Juveniles> |    
   
    | 70b.    Head somewhat less globular or at
    least orthognathous |    
   
    | 71a.    Antennae not with 12 segments
    or, if with 12, they arise from a prominence and the abdomen is long
    petiolate or its sides are acutely margined |    
   
    | 71b.    Females:  antennae with 12 segments
    and other characters different than previous ............ (Scolioidea) |    
   
    | 72a.    Pronotum fused to mesonotum; abdominal
    tergite 2 with a lateral felt line ............. (Tiphioidea)   [Now in Vespoidea] Mutillidae  (now with Sapygidae)  <Habits>; <Adults> & <Juveniles>] |    
   
    | 72b.    Pronotum separate from mesonotum;
    abdominal tergite 2 without a lateral felt line
    ........... (Tiphioidea)   [Now in
    Vespoidea]  Tiphiidae   <Habits>;
    <Adults> & <Juveniles> |      REFERENCES:   Benson,
  R. B.  1951-1958.  Hymenoptera, Symphyta. 
  handbk. Ident. Brit. Insects 6 (2a, b & c).   Borror,
  D. J. & D. M. DeLong.  1964.  An Introduction to the Study of Insects.  Holt, Rinehart & Winston, NY.  819      p.   Borror,
  D. J., G. A. Triplehorn & N. F. Johnson. 
  1989.  An Introduction to the
  Study of Insects, 6th ed.  Saunders   Publ. Co., Phila.  875 p.   Clausen,
  C. P.  1940.  Entomophagous Insects. 
  McGraw-Hill Book Co., NY.  688 p.  [reprinted 1962 by Hafner  Publ. Co., NY.].   Gauld, I.
  & B. Bolton.  1988.  The Hymenoptera. 
  British Mus. (Nat. Hist.), Oxford Univ. Press., NY.  332 p.       Hill, C.
  C.  1923.  Platygaster vernalis Myers, an important parasite
  of the Hessian fly.  J. Agr. Res. 25:  31-42.   Richards,
  O. W.  1977.  Hymenoptera Introduction and Key to Families, 2nd ed.  Roy Ent. Soc., London.  100 p.       |