Phylum Arthropoda (Arthropods) ➔ Subphylum Hexapoda (Hexapods) ➔ Class Insecta (Insects) ➔ Order Coleoptera (Beetles) ➔ Family Chrysomelidae (Leaf beetles)

Plagiosterna aenea (Linnaeus, 1758)

Erzfarbener Erlenblattkäfer

Synonyms:

Chrysomela aenea Linnaeus, 1758 | Chrysomela coeruleoviolacea De Geer, 1775 | Melasoma bicolor Schilsky, 1908 | Chrysomela fuscicornis Fabricius, 1781 | Chrysomela haemorrhoidalis O.F. Müller, 1776 | Chrysomela violacea Olivier, 1790 | Coccinella vitellinae Scopoli, 1763 |

  • Plagiosterna aenea  3019
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea
    DE, Chemnitz, Hutholz; 2008-07-06 12:54:52
    Image number: 3019

    DE, Chemnitz, Hutholz
    2008-07-06 12:54:52

  • Plagiosterna aenea  4088
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea
    DE, Chemnitz, Zeisigwald; 2010-07-03 11:20:16
    Image number: 4088

    DE, Chemnitz, Zeisigwald
    2010-07-03 11:20:16

  • Plagiosterna aenea  3097
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea
    DE, Chemnitz, Zeisigwald; 2006-05-21 14:36:32
    Image number: 3097

    DE, Chemnitz, Zeisigwald
    2006-05-21 14:36:32

  • Plagiosterna aenea  3081
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea
    DE, Chemnitz, Zeisigwald; 2007-06-30 15:24:12
    Image number: 3081

    DE, Chemnitz, Zeisigwald
    2007-06-30 15:24:12

  • Plagiosterna aenea  3133
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea
    DE, Chemnitz, Hutholz; 2005-04-24 14:11:07
    Image number: 3133

    DE, Chemnitz, Hutholz
    2005-04-24 14:11:07

  • Plagiosterna aenea  3164
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea; det. Klaas Reißmann
    DE, Chemnitz, Zeisigwald; 2006-07-15 10:23:37
    Image number: 3164

    DE, Chemnitz, Zeisigwald
    2006-07-15 10:23:37
    det. Klaas Reißmann
  • Plagiosterna aenea  3165
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea; det. Klaas Reißmann
    DE, Chemnitz, Zeisigwald; 2006-07-15 10:24:21
    Image number: 3165

    DE, Chemnitz, Zeisigwald
    2006-07-15 10:24:21
    det. Klaas Reißmann
  • Plagiosterna aenea, larva  8847
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, larva; conf. Christoph Benisch
    DE, Chemnitz, Stadtpark; 2019-07-15 16:23:45
    Image number: 8847
    larva
    DE, Chemnitz, Stadtpark
    2019-07-15 16:23:45
    conf. Christoph Benisch
  • Plagiosterna aenea, larva  8848
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, larva; conf. Christoph Benisch
    DE, Chemnitz, Stadtpark; 2019-07-15 16:23:31
    Image number: 8848
    larva
    DE, Chemnitz, Stadtpark
    2019-07-15 16:23:31
    conf. Christoph Benisch
  • Plagiosterna aenea, pre-pupa  8858
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, pre-pupa
    DE, Chemnitz, Stadtpark; 2019-07-18 10:38:50
    Image number: 8858
    pre-pupa
    DE, Chemnitz, Stadtpark
    2019-07-18 10:38:50

  • Plagiosterna aenea, pupa  8859
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, pupa
    DE, Chemnitz, Stadtpark; 2019-07-21 12:17:44
    Image number: 8859
    pupa
    DE, Chemnitz, Stadtpark
    2019-07-21 12:17:44

  • Plagiosterna aenea, pupa  8860
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, pupa
    DE, Chemnitz, Stadtpark; 2019-07-21 12:19:27
    Image number: 8860
    pupa
    DE, Chemnitz, Stadtpark
    2019-07-21 12:19:27

  • Plagiosterna aenea, freshly hatched  8861
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, freshly hatched
    DE, Chemnitz, Stadtpark; 2019-07-22 08:31:29
    Image number: 8861
    freshly hatched
    DE, Chemnitz, Stadtpark
    2019-07-22 08:31:29

  • Plagiosterna aenea, pupa  6239
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, pupa; conf. Klaas Reißmann
    DE, Chemnitz, Harthwald; 2013-07-24 10:15:53
    Image number: 6239
    pupa
    DE, Chemnitz, Harthwald
    2013-07-24 10:15:53
    conf. Klaas Reißmann
  • Plagiosterna aenea, pupa  6240
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, pupa
    DE, Chemnitz, Harthwald; 2013-07-24 10:19:35
    Image number: 6240
    pupa
    DE, Chemnitz, Harthwald
    2013-07-24 10:19:35

  • Plagiosterna aenea, freshly hatched  6241
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, freshly hatched; conf. Klaas Reißmann
    DE, Chemnitz, Harthwald; 2013-07-27 15:44:04
    Image number: 6241
    freshly hatched
    DE, Chemnitz, Harthwald
    2013-07-27 15:44:04
    conf. Klaas Reißmann
  • Plagiosterna aenea, freshly hatched  6242
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, freshly hatched
    DE, Chemnitz, Harthwald; 2013-07-27 15:47:33
    Image number: 6242
    freshly hatched
    DE, Chemnitz, Harthwald
    2013-07-27 15:47:33

  • Plagiosterna aenea, freshly hatched  6243
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, freshly hatched
    DE, Chemnitz, Harthwald; 2013-07-27 15:50:25
    Image number: 6243
    freshly hatched
    DE, Chemnitz, Harthwald
    2013-07-27 15:50:25

  • Plagiosterna aenea, 4 hours later  6244
    Plagiosterna aenea (Linnaeus, 1758)  Erzfarbener Erlenblattkäfer   
    Plagiosterna aenea, 4 hours later; conf. Klaas Reißmann
    DE, Chemnitz, Harthwald; 2013-07-27 19:42:25
    Image number: 6244
    4 hours later
    DE, Chemnitz, Harthwald
    2013-07-27 19:42:25
    conf. Klaas Reißmann

Classification:
Plagiosterna aenea belongs to the subfamily Chrysomelinae, tribe Chrysomelini.
Distribution:
Europe (except Scandinavia), in parts of Asia.
Habitat:
In alluvial forests, brook valleys and at water margins on alders.
Description:
Length 6.5 - 8.5 mm; body metallic green, red-gold or blue; elytra much wider than the pronotum, with strongly set off lateral bulge, disorderly dotted; pronotum without well set off lateral bulge, dotting of the pronotum in the middle slight, at the sides coarser and uneven; tibiae at the outer rim with imperfect furrow; 3rd segment of tarsi weakly cut out at the tip.
Plagiosterna aenea is the only species of the genus Plagiosterna in Europe.
Biology:
Plagiosterna aenea lives on different alder species. Host plants in Central Europe are black alder (Alnus glutinosa), grey alder (Alnus incana) and Alnus alnobetula.
The adults of Plagiosterna aenea appear at the end of April from their winter shelter and start feeding on the leaves of the host plants. They are macropter and able to fly, but rarely fly. The yellowish eggs are laid by the females in small groups of about 25 - 30 eggs on the undersides of the leaves. After approximately 7 days, the larvae hatch. They pass through 3 larval stages in 18 - 22 days. The larvae feed in the first days in the group and spread later individually on the leaves. The adult larvae attach themselves to a leaf with the rear end for pupation. The pupal stage lasts about a week. The new beetle generation hatches in July/August. The entire development takes about 5 weeks. The beetles undergo a maturation feeding period of about 2 weeks, retreat from mid-August to undergo a long autumn and winter diapause. They usually spend the winter in forests at dry places in the leaf layer.
The species normally forms one generation per year in Germany. In climatically more favourable locations in Southern Europe, 2 generations can also be passed through.
Note:
The pictures from 2013 show a pupa of Plagiosterna aenea and the beetle with the empty pupal shell hatched 3 days later. Shortly after hatching the beetle, which was still predominantly light with dark pronotum, legs and antennae, changed colour and showed its final metallic blue basic colouring only 4 hours later.
The last instar larva found in 2019 was in a hurry to grow up. Only 4 days after it had freed itself from last larval skin, the metamorphosis to the adult beetle was completed.

References, further reading, links:
  1. Rheinheimer, Joachim, & Hassler, Michael: Die Blattkäfer Baden-Württembergs, 2018, 928 pages, Kleinsteuber Books (Karlsruhe), ISBN 978-3-9818110-2-5
  2. Arved Lompe: Die Käfer Europas - Ein Bestimmungswerk im Internet