Phylum Arthropoda (Arthropods) ➔ Subphylum Hexapoda (Hexapods) ➔ Class Insecta (Insects) ➔ Order Coleoptera (Beetles) ➔ Family Curculionidae (Weevils)

Stereonychus fraxini (De Geer, 1775)

Eschenrüssler Ash Weevil

Synonyms and other combinations:

Curculio fraxini De Geer, 1775 |

  • Stereonychus fraxini 2970
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini, det. Christoph Benisch
    DE, Chemnitz; 2008-05-11 09:38:14
    Image number: 2970

    DE, Chemnitz
    2008-05-11 09:38:14
    det. Christoph Benisch
  • Stereonychus fraxini 3054
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini
    DE, Chemnitz, Zeisigwald; 2009-04-26 11:04:38
    Image number: 3054

    DE, Chemnitz, Zeisigwald
    2009-04-26 11:04:38
  • Stereonychus fraxini 3053
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini
    DE, Chemnitz, Zeisigwald; 2009-04-26 11:04:55
    Image number: 3053

    DE, Chemnitz, Zeisigwald
    2009-04-26 11:04:55
  • Stereonychus fraxini, larva 8257
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini, larva, conf. Christoph Benisch
    DE, Chemnitz, Hutholz; 2018-05-28 11:15:16
    Image number: 8257
    larva
    DE, Chemnitz, Hutholz
    2018-05-28 11:15:16
    conf. Christoph Benisch
  • Stereonychus fraxini, larva 8258
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini, larva, conf. Christoph Benisch
    DE, Chemnitz, Hutholz; 2018-05-28 15:19:13
    Image number: 8258
    larva
    DE, Chemnitz, Hutholz
    2018-05-28 15:19:13
    conf. Christoph Benisch
  • Stereonychus fraxini, cocoon 8259
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini, cocoon, conf. Christoph Benisch
    DE, Chemnitz, Hutholz; 2018-05-29 15:52:54
    Image number: 8259
    cocoon
    DE, Chemnitz, Hutholz
    2018-05-29 15:52:54
    conf. Christoph Benisch
  • Stereonychus fraxini, cocoon 8260
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini, cocoon, conf. Christoph Benisch
    DE, Chemnitz, Hutholz; 2018-05-29 15:54:52
    Image number: 8260
    cocoon
    DE, Chemnitz, Hutholz
    2018-05-29 15:54:52
    conf. Christoph Benisch
  • Stereonychus fraxini, 8270
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini,
    DE, Chemnitz, Hutholz; 2018-06-05 14:21:03
    Image number: 8270

    DE, Chemnitz, Hutholz
    2018-06-05 14:21:03
  • Stereonychus fraxini 8271
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini
    DE, Chemnitz, Hutholz; 2018-06-05 14:18:37
    Image number: 8271

    DE, Chemnitz, Hutholz
    2018-06-05 14:18:37
  • Stereonychus fraxini 8272
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini
    DE, Chemnitz, Hutholz; 2018-06-05 17:20:04
    Image number: 8272

    DE, Chemnitz, Hutholz
    2018-06-05 17:20:04
  • Stereonychus fraxini 8273
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini
    DE, Chemnitz, Hutholz; 2018-06-06 10:16:24
    Image number: 8273

    DE, Chemnitz, Hutholz
    2018-06-06 10:16:24
  • Stereonychus fraxini 8282
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini
    DE, Chemnitz, Hutholz; 2018-06-08 16:05:52
    Image number: 8282

    DE, Chemnitz, Hutholz
    2018-06-08 16:05:52
  • Stereonychus fraxini, feeding pattern 8283
    Stereonychus fraxini (De Geer, 1775)  Eschenrüssler  Ash Weevil 
    Stereonychus fraxini, feeding pattern
    DE, Chemnitz, Hutholz; 2018-06-08 16:03:50
    Image number: 8283
    feeding pattern
    DE, Chemnitz, Hutholz
    2018-06-08 16:03:50

Further vernacular names:
Slimy Ash Weevil, Olive Leaf Weevil
Distribution:
Europe (except the far north), North Africa
Habitat:
Deciduous forests, mostly on ash trees.
Description:
The 2.5 - 3.2 mm large ash weevil has a dark, black or brown body. The upper side is covered with closely fitting grey, brown and black scales. The center of the neck shield usually shows a broad dark longitudinal band. The antennae and legs are partly lighter brownish. The tarsi have only one claw. Beside brighter shaded beetles (2nd and 3rd picture) there are also predominantly black-brown colored specimens (1st picture) with bright neck shield sides.
Biology:
The ash weevil (Stereonychus fraxini) hibernates as an imago in the litter. After the end of the diapause, the wintered, oligophagous beetles can be found on their host plants, mostly ashes. They eat freshly sprouting buds and also leaves. About 12 to 22 days later, the females begin to lay their eggs on the underside of leaves. After 9 to 11 days, the larvae hatch and begin to scrape the top of leaves, creating fenestrate feeding pattern. The larvae pass through 3 larval stages in 16 - 20 days. The adult larvae secrete a slimy layer that hardens into a yellowish-brown cocoon. The pupation takes place in the approx. 3 mm large cocoon. Since the walls of the cocoon are transparent, one can observe the movements of the pupa inside.
After about 7 - 10 days the new beetle generation hatches. The beetles feed holes in the leaves of their host plants and also in their buds, thus preparing themselves for the subsequent wintering.
Stereonychus fraxini forms one generation per year.
Note:
The last picture shows the holes in the leaves caused in 3 days by the small beetle hatched on June 5th.

References, further reading, links:
  1. Arved Lompe: Die Käfer Europas - Ein Bestimmungswerk im Internet
  2. Milan Drekić, Leopold Poljaković-Pajnik, Verica Vasić, Predrag Pap, Andrej Pilipović: Contribution to the Study of Biology of Ash Weevil (Stereonychus fraxini De Geer), Šumarski list, 7–8, CXXXVIII (2014), 387–395