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Aeshna juncea (Linnaeus) Common hawker Description A. juncea is a large hawker dragonfly, males of which have blue spots and Habitat Flight periods Status and distribution European and world distribution yellow markings on a dark brown-black body, and are thus similar to A. cyanea, A. mixta and Brachytron pratense. In males, the paired blue spots on the dorsal surface of abdominal segments 9 and 10 are separated, unlike those of A. cyanea in which they are joined into two broad blue bands. The yellow antehumeral stripes are much thinner than those of A. cyanea, but are more extensive than those of A. mixta. The costa is bright yellow, distinguishing A. juncea from the other three species, in which it is brown. Both male and female A. juncea lack the very hairy thorax of B. pratense; also, their pterostigmata are not as elongated, and they are much larger. In female A. juncea, yellow to green usually replaces the blue coloration on males, and the antehumeral stripes are reduced to two thin lines. A. juncea typically breeds in bog pools, the margins of ponds and lakes in moorland and heathland areas, and occasionally in slow-flowing sections of upland streams. Such sites are generally of an acidic nature and range from oligotrophic to slightly mesotrophic. Less commonly, A. juncea may breed in peaty fens, more often in Ireland than in Britain. Breeding biology Males are territorial; highest steady density being about 2 per 100 m of water's edge. Where they occur with A. cyanea on small ponds, A. cyanea generally drives them out (Moore 1964), Copulation takes place amongst heather, bushes and trees, and lasts for 60-75 minutes. Females oviposit alone, inserting their eggs into submerged tissues of plants such as pondweeds and rushes or, occasionally, into soft peaty mud. This may take place in quite dull weather, and the rustling of wings low down amongst emergent vegetation may be the first indication to an observer that a dragonfly is present. Such rustling is the result of wing-whirring, which is a means of gaining and maintaining body heat in low temperatures, and is a device practised by many of the larger dragonfly species. The eggs pass the winter in diapause, and larvae take two or more years to develop. As in other aeshnids, the larvae live amongst submerged vegetation, or plant remains, and catch their prey by remaining motionless and concealed, strildng out when an item of food comes within range. Occasionally, they will actively pursue their prey over very short distances. Emergence often occurs on the stems of common cottongrass and rushes. A. juncea is on the wing from early July to early October. The males spend much time feeding over moorland or along rides in conifer plantations, often far from water. A. juncea is often found with other species which can tolerate oligotrophic, acidic conditions, such as Sympetrum danae, Libellula quadrimaculata, Lestes sponsa and Pyrrhosoma nymphula. A. juncea occurs most commonly in upland areas of Britain and Ireland, and on lowland heaths and moors. It is absent or very scarce in the English east midlands, East Anglia, Kent and Sussex, owing to a lack of suitable habitat, and has probably declined in some areas in recent years as a result of the reclamation of lowland heaths for agriculture, forestry and urban development. A. juncea is an holarctic species found throughout northern and central Europe, with southern outposts in mountain areas. It occurs east to Siberia and Japan, and in Alaska, Canada and northern USA. 66
Aeshna juncea (Linnaeus) Common hawker 1975-90 o 1950-74 O Pre-1950 o 00111 , r;c3° 04111 00:106:i: . !I:7060:6 00000 6 . 009 00 041 0 00 410 0 s e 0 00 000' 00000 00 00 00000 0 00 o 000 0 00 00 0000 0(30 oo 0 00 00 0 000 00 o ' 00 Oo 411 0000 0 o. o 0041 000 o 000 0 00 000 00 00 000 000. o 00 o 00 N . op 05 0041, 0000 o 00 0 o 0 00 0 41000 0000 00 00000 4100 o 000 00 0 00 05 o 0 0 00 00 o o o 0 0 000 050 00 00 0000 0 000 00 o 00000 00 15115 0 000 0 000 00 00 o 0 o 0 0 000000 00 67 00000 000 0 oe 00 0 000 000 o
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Cover photograph: Aeshna juncea Ins
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@ NERC Copyright 1996 ISBN 0 11 701
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FOREWORD Having been on the fringe
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ACKNOWLEDGMENTS The following list
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Howard, G.; Howard, LW; Howe, M.; H
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Walker, D.S.; Walker, FA; WaLker, I
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CHECKLIST The following checklist i
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Aeshna mixta Latreille 1805 Aeschna
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THE BRITISH AND IRISH ODONATA IN A
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of distributions of dragonflies usi
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I 00 o o Figure 3. Map of coverage
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,o " Figure 5. Map of coverage at t
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FIELDWORK AND DATA MANAGEMENT METHO
Page 30 and 31: areas, and encouraged in this by bo
Page 32 and 33: Table 3. Distribution of each speci
Page 34 and 35: Table 4 (con°. Vice-county distrib
Page 36 and 37: Table 4 (cont). Vice-county distrib
Page 38 and 39: Computerisation and validation Havi
Page 40 and 41: dominance of one individual over an
Page 42 and 43: RESIDENT SPECIES Description Habita
Page 44 and 45: Calopteryx splendens (Harris) Bande
Page 46 and 47: Description Flight periods Status a
Page 48: Description Lestes dryas Kirby Scar
Page 51 and 52: Platycnemis pennipes (Pallas) White
Page 53 and 54: Pyrrhosoma nymphula (Sulzer) 1975-9
Page 55 and 56: Erythromma najas (Hansemann) 1975-9
Page 57 and 58: Coenagrion mercuriale (Charpentier)
Page 59 and 60: Coenagrion scituluni (Rambur) Daint
Page 61 and 62: Coenagrion hastulatuni (Charpentier
Page 63 and 64: Coenagrion lunulatum (Charpentier)
Page 65 and 66: Coenagrion armatum (Charpentier) No
Page 67 and 68: Coenagrion puella (Linnaeus) Azuxe
Page 69 and 70: Coenagrion pulchellum (Vander Linde
Page 71 and 72: Enallagma cyathigerurn (Charpentier
Page 73 and 74: Ischnura pumilio (Charpentier) Scar
Page 75 and 76: Ischnura elegans (Vander Linden) 19
Page 77 and 78: Ceriagrion tenellurn (Villers) 1975
Page 79: Aeshna caerulea (Strom) Azure hawke
Page 83 and 84: Montiaghs Moss, near Aghalee, Co An
Page 85 and 86: Sundon Springs chalk quarry, near L
Page 87 and 88: PLATE 1 Calopteryxvirgo adult PLATE
Page 89 and 90: PLATE 13 Libellula fulva adult PLAT
Page 91 and 92: Aeshna mixta Latreile Migrant hawke
Page 93 and 94: Aeshna cyanea (Muller) Southern haw
Page 95 and 96: Aeshna grandis (Linnaeus) Brown haw
Page 97 and 98: Aeshna isosceles (Muller) Norfolk h
Page 99 and 100: Anax imperator Leach Emperor dragon
Page 101 and 102: Brachytron pratense (Muller) Hairy
Page 103 and 104: Gomphus vulgatissimus (Linnaeus) 19
Page 105 and 106: Cordulegaster boltonii (Donovan) Go
Page 107 and 108: Cordulia aenea (Lin.naens) Downy em
Page 109 and 110: Somatochlora metallica (Vander Lind
Page 111 and 112: Somatochlora arctica (Zetterstedt)
Page 113 and 114: Oxygastra curtisii (Dale) Orange-sp
Page 115 and 116: Libellula quadrimaculata Linnaeus 1
Page 117 and 118: Libellula fulva Mailer Scarce chase
Page 119 and 120: Libellula depressa Linnaeus 1975-90
Page 121 and 122: Orthetrum cancellatum (Linnaeus) 19
Page 123 and 124: Orthetrum coerulescens (Fabricius)
Page 125 and 126: Sympetrum striolaturn (Charpentier)
Page 127 and 128: Sympetrum sanguineum (Muller) Ruddy
Page 129 and 130: Sympetruni danae (Sulzer) 1975-90 o
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Leuconhinia dubia (Vander Linden) W
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IMIVLIGRANTS AND ACCIDENTAL SPECIES
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POSSIBLE ADDITIONS TO THE BRITISH A
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SEASONAL OCCURRENCE PREVIOUS REPRES
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700 600 500 400 300. 200 100 0 90 8
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70 60 50 40 30 20 10 90 80 70 60 50
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Finally, differences in recorder be
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ODONATA LOCALITY 6411 V10E-COUNTY N
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Particularly in the case of residen
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conditions and which may be of grea
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1960s from its single locality alon
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pond. One of the authors did this o
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REFERENCES Aguilar, J. d', Dommange
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Gabb, R. & Kitching, D. 1992. The d
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Coenagrion rnercuriale (Charpentier
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Dee'. Transactions of the Natural H
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Circumboreal Occurring in a band en
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Marl A whitish clay soil with a hig
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Vulvar scale WATCH Weald Wheel posi
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Appendix 2. LIST OF PLANT NAMES Pla
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Libefiula depressa 5,6,14,17,18,19,
show all

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