Insects of Britain and Ireland: the families of Hemiptera

L. Watson and M.J. Dallwitz

Conventional key

If you are serious about identification, you should use the interactive key. It is far superior, with flexible choice of characters, character notes and illustrations, error tolerance, full taxon descriptions, and taxon illustrations.

1(0).

Rostrum clearly separated ventrally from the prosternum by a sclerotized gula (the rostrum brought forwards: Heteroptera) ... 2 Rostrum not separated from the prosternum by a gula (inserted further back, under or apparently behind the head: Homoptera)... 55

2(1).

Fore-wings well developed: more or less equalling or exceeding the abdomen when folded ... 3 Fore-wings conspicuous, but much shorter than the abdomen... 35 Fore-wings vestigial or absent... 40

3(2).

terrestrial ... 4 dwelling (skating) on the surface of water... 27 foraging under water... 31

4(3).

Scutellum very large, at least half as long as thedistance from the hind margin of the pronotum to the tip of the abdomen ... 5 Scutellum relatively small, shorter than half the distance from the hind margin of the pronotum to the tip of the abdomen... 7

5(4).

The second visible abdominal sternite with a long,spine-like, forwardly directed anterior process; tarsi 2 segmented ... Acanthosomatidae The second visible abdominal sternite without a long, spine-like anterior process; tarsi 3 segmented... 6

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6(5).

The abdominal tergites with 6 visible connexivia ... Cydnidae The abdominal tergites with 7 visible connexivia ... Scutelleridae, Pentatomidae

7(4).

Fore-wings with a costal fracture and cuneus ... 8 Fore-wings without costal fracture and cuneus... 12

8(7).

Rostrum 3 segmented ... 9 Rostrum 4 segmented... 10

9(8).

Antennae with segments 3 + 4 very slender, and twice as long as segments 1 + 2 ... Dipsocoridae Antennae with segments 3 + 4 less than twice as long as 1 + 2 ... Anthocoridae

10(8).

Trochanters apparently two-segmented ... Miridae Trochanters not apparently segmented... 11

11(10).

relatively stout bodied; tarsi 2 segmented ... Microphysidae with narrow-elongate bodies; tarsi 3 segmented ... Nabidae

12(7).

phytophagous ... 13 mycophagous ... Aradidae predacious... 22 feeding on dead arthropods... 26

13(12).

Ocelli present ... 14 Ocelli absent... 21

14(13).

Tarsi 2 segmented ... 15 Tarsi 3 segmented... 16

15(14).

tiny ... Piesmatidae small ... Coreidae large ... Coreidae

16(14).

Head strongly transversely grooved (constricted) between the eyes ... Berytinidae Head not transversely grooved between the eyes... 17

17(16).

Antennae from the upper part of the head; membrane of the hemelytron with numerous veins reaching or almost reaching the margin ... 18 Antennae from the lower part of the head; membrane of the hemelytron with 4 or 5 veins reaching or almost reaching the margin ... Lygaeidae

18(17).

with conspicuous dark-and-pale banding on theantennae and legs ... Stenocephalidae without conspicuous dark-and-pale banding of antennae and legs... 19

19(18).

Metathorax with a repugnatorial scent-gland opening, comprising a funnel surrounded by a dull patch of elaborately sculptured cuticle, visible laterally on either side (near the coxae of the hind-legs); the second dorsal abdominal scent gland aperture not displaced into the fifth tergite, and distant from the first gland ... 20 Metathorax without laterally visible scent gland openings; the second dorsal abdominal scent gland aperture displaced forwards into the fifth tergite, thus close to that of the first gland ... Rhopalidae

20(19).

relatively stout bodied ... Coreidae with narrow-elongate bodies ... Alydidae

21(13).

Fore-wings finely reticulate or areolate throughout ... Tingidae Fore-wings not finely reticulate throughout ... Pyrrhocoridae

22(12).

Head strongly transversely grooved (constricted) between the eyes ... Reduviidae Head not transversely grooved between the eyes... 23

23(22).

conspicuous jumpers ... Saldidae not jumpers... 24

24(23).

Pulvilli present; the abdomen without ventral silvery pubescence ... Lygaeidae Pulvilli absent; the abdomen covered ventrally with dense, silvery pubescence... 25

25(24).

conspicuously stilt-legged; rostrum 3 segmented; antennae 4 segmented; tarsi 3 segmented ... Mesovelidae not stilt-legged; rostrum 4 segmented; antennae 5 segmented; tarsi 2 segmented ... Hebridae

26(12).

conspicuously stilt-legged; rostrum 3 segmented; antennae 4 segmented; tarsi 3 segmented ... Mesovelidae not stilt-legged; rostrum 4 segmented; antennae 5 segmented; tarsi 2 segmented ... Hebridae

27(3).

Claws all apical ... 28 Claws of at least of the fore-legs inserted short of the tip of the terminal segment... 30

28(27).

relatively stout bodied; head non-linear, no more than twice as long as wide; tiny ... 29 with narrow-elongate bodies; head linear, several times longer than wide; large ... Hydrometridae

29(28).

conspicuously stilt-legged; rostrum 3 segmented; antennae 4 segmented; tarsi 3 segmented ... Mesovelidae not stilt-legged; rostrum 4 segmented; antennae 5 segmented; tarsi 2 segmented ... Hebridae

30(27).

Rostrum 3 segmented; the second visible abdominal sternite without a long, spine-like anterior process; not stilt-legged ... Veliidae Rostrum 4 segmented; the second visible abdominal sternite with a long, spine-like, forwardly directed anterior process; conspicuously stilt-legged ... Gerrididae

31(3).

Swimming and moving under water on their backs ... 32 Swimming and moving under water the right way up... 33

32(31).

Rostrum 3 segmented; up to 5 mm long; antennae1 to 3 segmented; tiny ... Pleidae Rostrum 4 segmented; 10 to 20 mm long; antennae 4 segmented; large ... Notonectidae

33(31).

Fore-legs modified and raptorial ... 34 Fore-legs non-raptorial ... Corixidae

34(33).

The abdomen terminating in a long, bristle-like respiratory siphon ... Nepidae The abdomen without a respiratory siphon ... Naucocoridae

35(2).

phytophagous ... 36 mycophagous ... Aradidae predacious... 37 feeding on dead arthropods ... Aepophilidae

36(35).

Ocelli present; metathorax without laterally visible scent gland openings ... Rhopalidae Ocelli absent; metathorax with a repugnatorial scent-gland opening, comprising a funnel surrounded by a dull patch of elaborately sculptured cuticle, visible laterally on either side (near the coxae of the hind-legs) ... Pyrrhocoridae

37(35).

Antennae longer than the head, readily visiblefrom above ... 38 Antennae inserted underneath the head and much shorter than it, generally invisible from above ... Aphelocheiridae

38(37).

Rostrum 3 segmented ... 39 Rostrum 4 segmented ... Microphysidae

39(38).

conspicuous jumpers; ocelli present ... Saldidae not jumpers; ocelli absent ... Aepophilidae

40(2).

Rostrum 3 segmented ... 41 Rostrum 4 segmented... 48

41(40).

Head strongly transversely grooved (constricted) between the eyes ... Reduviidae Head not transversely grooved between the eyes... 42

42(41).

terrestrial ... 43 dwelling (skating) on the surface of water... 46

43(42).

conspicuous jumpers ... Saldidae not jumpers... 44

44(43).

conspicuously stilt-legged; the abdomen covered ventrally with dense, silvery pubescence ... Mesovelidae not stilt-legged; the abdomen without ventral silvery pubescence... 45

45(44).

Ocelli present ... Anthocoridae Ocelli absent ... Cimicidae

46(42).

conspicuously stilt-legged; claws all apical ... 47 not stilt-legged; claws of at least of the fore-legs inserted short of the tip of the terminal segment ... Veliidae

47(46).

relatively stout bodied; head non-linear, no more than twice as long as wide; tiny ... Mesovelidae with narrow-elongate bodies; head linear, several times longer than wide; large ... Hydrometridae

48(40).

phytophagous ... 49 mycophagous ... Aradidae predacious... 52 feeding on dead arthropods... 54 blood-suckers ... Cimicidae

49(48).

Head strongly transversely grooved (constricted) between the eyes ... Berytinidae Head not transversely grooved between the eyes... 50

50(49).

Antennae from the upper part of the head ... 51 Antennae from the lower part of the head ... Lygaeidae

51(50).

relatively stout bodied ... Coreidae with narrow-elongate bodies ... Alydidae

52(48).

The second visible abdominal sternite with a long, spine-like, forwardly directed anterior process; conspicuously stilt-legged ... Gerrididae The second visible abdominal sternite without a long, spine-like anterior process; not stilt-legged... 53

53(52).

Antennae 4 segmented; tarsi 3 segmented; the abdomen without ventral silvery pubescence; pulvilli present ... Lygaeidae Antennae 5 segmented; tarsi 2 segmented; the abdomen covered ventrally with dense, silvery pubescence; pulvilli absent ... Hebridae

54(48).

relatively stout bodied; not stilt-legged; antennae 5 segmented; claws all apical; the second visible abdominal sternite without a long, spine-like anterior process ... Hebridae with narrow-elongate bodies; conspicuously stilt-legged; antennae 4 segmented; claws of at least of the fore-legs inserted short of the tip of the terminal segment; the second visible abdominal sternite with a long, spine-like, forwardly directed anterior process ... Gerrididae

55(1).

Rostrum clearly arising from the head; antennae consisting of short segments with a terminal, unsegmented arista that is much longer than the segments ... 56 Rostrum ostensibly originating between the front legs; antennae non-aristate... 63

56(55).

conspicuous jumpers ... 57 not jumpers... 60

57(56).

The posterior tibiae with a large, moveable apical spur; tegulae present; clavus with two veins uniting posteriorly to form a Y ... Delphacidae The posterior tibiae without a large, moveable apical spur; tegulae absent; clavus without convergence of veins to form a Y... 58

58(57).

Hind coxae mobile; the posterior tibiae cylindrical ... Cercopidae Hind coxae immobile; the posterior tibiae longitudinally keeled... 59

59(58).

Fore-wings with transparent cells; thorax conspicuously crested ... Membracidae Fore-wings with opaque cells; thorax not crested ... Cicadellidae

60(56).

Ocelli present ... 61 Ocelli absent ... Issidae

61(60).

Tegulae present; fore-wings without conspicuously raised, reticulate venation; hind coxae immobile ... 62 Tegulae absent; fore-wings with conspicuously raised, reticulate venation; hind coxae mobile ... Cicadidae

62(61).

Fore-wings with transparent cells ... Cixiidae Fore-wings with opaque cells ... Tettigometridae

63(55).

represented by both greatly reduced, sedentary forms and ‘normal’, mobile insects ... 64 represented by ‘normal’ insects only... 65

64(63).

Tarsi 1 segmented; tarsi one-clawed ... Superfamily Coccoidea Tarsi 2 segmented; tarsi two-clawed ... Phylloxeridae

65(63).

conspicuous jumpers ... Psyllidae not jumpers... 66

66(65).

Head plus thorax of apterae greater in volume than the abdomen ... 67 Head plus thorax of apterae not exceeding that of the abdomen... 68

67(66).

Antennae 1 to 3 segmented; small ... Adelgidae Antennae 7 segmented; tiny ... Aleyrodidae

68(66).

The abdomen equipped with a pair of secretory ‘cornicles’ (siphunculi) towards the rear ... Pemphigidae, Aphididae The abdomen without secretory ‘cornicles’... 69

69(68).

Antennae 1 to 3 segmented ... Pemphigidae Antennae 4 segmented ... Pemphigidae Antennae 5 segmented ... Pemphigidae Antennae 6 segmented ... Pemphigidae Antennae 7 segmented ... Aleyrodidae

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the families of Hemiptera. Version: 27th July 2019. delta-intkey.com’.

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