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Libellula depressa Linnaeus Broad-bodied chaser Description The very broad, flattened and pale blue abdomen of mature male L. depressa, and the large black-brown patch at the base of each wing distinguish this species from the three other male libellulids that possess a blue abdomen. In immature males and in females, the abdomen is yellowish brown with yellow markings laterally which are most prominent on segments 4-7. In males, a blue pruinescence develops with age and covers the abdomen, except for segments 1, 2 and 10 which remain dark, and the lateral yellow markings which may be slightly reduced in size. The pattern of markings on the wings is the same in both sexes although, in the female, the dark basal patches are more heavily marked with yellow veins than in males. These wing markings and the very broad short abdomen distinguish females from those of other libellulids. The thorax is dark brown in both sexes, with two pale whitish stripes dorsally. The eyes are dark brown. Habitat L. depressa breeds in well-vegetated ponds, lakes, canals and ditches. However, it is also one of the first dragonflies to colonise a newly created water body and will breed in small garden ponds, and in farm ponds that are mildly polluted. In south-west Britain, it occasionally breeds in peaty bog pools. Breeding biology The male is territorial and very aggressive. The population density of males rarely exceeds 8 per 100 m of water's edge. Therefore, small ponds will seldom if ever hold more than one male. As with other large libellulids, males perch on stems of tall emergent plants or on exposed sticks and make frequent flights to chase off intruding males, returning to the same perch. Copulation occurs in flight and only takes a few seconds. During oviposition, the female flies very low in and out of the vegetation at the water margin and thrusts her eggs into the water by flicking her abdomen downwards. Males sometimes guard females during this process, but females frequently oviposit alone and when no male is present at a pond. The eggs hatch after two to three weeks and the larvae, which live amongst the plant debris or silt at the bottom of the pond, probably take two or three years to develop in most circumstances, but can complete their life cycle in one year (Holmes & Randolph 1994). Emergence is usually synchronous, and takes place on marginal and emergent vegetation. Flight periods L. depressa is on the wing from mid-May to early August. On larger ponds and Status and distribution European and world distribution lakes it may be seen with species such as Anax imperator, Aeshna grandis, Orthetrurn cancellatum and the common damselllies. L. depressa is found widely in southern Britain, thinning out in the north midlands. It has conspicuously declined in eastern England from the Fens to Yorkshire, having been lost from many former sites owing to agricultural pressures, especially the loss of farm ponds. However, there are some signs of a recovery in recent years. There is a single record from Ireland. Miss Ball, a celebrated entomologist, recorded it from Glendine, Co Waterford, in July 1834. It is unlikely that a mistake could have been made in the identification of this distinctive species as the specimen was identified by Sélys-Longchamps (1846). An Irish specimen, possibly that of Miss Ball, is in Trinity College Museum, Dublin (King & Halbert 1910). L. depressa occurs throughout Europe as far north as southern Scandinavia, and east to the Middle East and western Asia. It is absent from North Africa. 96
Libellula depressa Linnaeus 1975-90 o 1950-74 O Pre-1950 , 69° 3 00.00000 0 00 00 97 00 0 Broad-bodied chaser 0 o 00 00 o o 00 000 000 0000 0 0 00 0 I 4100 00 0 0 000 0 0 o o eee 00 0000 000 00 00 00 0 000 000 000 0 0 0 00 00 0 00 0000 0000 00 Ole 00 000 1001 00 100 0 0 00 0 000000 00 00 0000000 00 0 00 000 00 00 00 000 00 000 000 00 ' 00000 00 0000 0 00 000000 00 000 00 00 00000 0000 00000 0000 00 0000 0000000 0000 0 000 00000000 0000 00 000000 0000 00 00000000 0 *00 00 000 00 00000 00 41,04,0 um 0 000000 0
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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
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areas, and encouraged in this by bo
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Table 3. Distribution of each speci
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Table 4 (con°. Vice-county distrib
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Table 4 (cont). Vice-county distrib
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Computerisation and validation Havi
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dominance of one individual over an
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RESIDENT SPECIES Description Habita
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Calopteryx splendens (Harris) Bande
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Description Flight periods Status a
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Description Lestes dryas Kirby Scar
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Platycnemis pennipes (Pallas) White
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Pyrrhosoma nymphula (Sulzer) 1975-9
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Erythromma najas (Hansemann) 1975-9
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Coenagrion mercuriale (Charpentier)
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Coenagrion scituluni (Rambur) Daint
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Coenagrion hastulatuni (Charpentier
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Coenagrion lunulatum (Charpentier)
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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 and 80: Aeshna caerulea (Strom) Azure hawke
Page 81 and 82: Aeshna juncea (Linnaeus) Common haw
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: Libellula fulva Mailer Scarce chase
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
Page 131 and 132: Leuconhinia dubia (Vander Linden) W
Page 133 and 134: IMIVLIGRANTS AND ACCIDENTAL SPECIES
Page 135 and 136: POSSIBLE ADDITIONS TO THE BRITISH A
Page 137 and 138: SEASONAL OCCURRENCE PREVIOUS REPRES
Page 139 and 140: 700 600 500 400 300. 200 100 0 90 8
Page 141 and 142: 70 60 50 40 30 20 10 90 80 70 60 50
Page 143 and 144: Finally, differences in recorder be
Page 145 and 146: ODONATA LOCALITY 6411 V10E-COUNTY N
Page 147 and 148: Particularly in the case of residen
Page 149 and 150: conditions and which may be of grea
Page 151 and 152: 1960s from its single locality alon
Page 153 and 154: pond. One of the authors did this o
Page 155 and 156: REFERENCES Aguilar, J. d', Dommange
Page 157 and 158: Gabb, R. & Kitching, D. 1992. The d
Page 159 and 160: Coenagrion rnercuriale (Charpentier
Page 161 and 162: Dee'. Transactions of the Natural H
Page 163 and 164: Circumboreal Occurring in a band en
Page 165 and 166: Marl A whitish clay soil with a hig
Page 167 and 168: 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,
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