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Lepidosaphes ulmi (L.)
Mytilococcus ulmi

Insecta, Homoptera, Diaspididae .

Oystershell scale, Mussel scale

Description, Biology, Life Cycle, Damage, Common Names, Images

- Female adult: scale pale or dark brown, 2-3.5 mm long, egg-shaped, elongate and often comma-shaped (*) ; cast skins pile up at the anterior part of the scale (*) .
- Eggs oval and white.
- Nymphs yellowish-brown, mobile and egg-shaped.

- Host plant: being very polyphagous, this scale insect feeds on fruit trees, forest trees and ornamentals. Common on apple and pear, it also develops on olive, plum, apricot and walnut.
- The insects imbibe the contents of plant cells.

[R]Life Cycle
There is 1 generation per year.
Eggs overwinter under the female's scale and hatch from May onwards. Young nymphs are initially mobile but settle on the twigs and branches 2 to 3 days after natching. After 2 moults, they become females in June and July. Females reproduce parthenogenetically in the autumn. Each lays 40 to 80 eggs and then dies, the eggs overwintering under the scale.

- Infestations cause encrustations to appear on branches (*) , twigs and fruits (*) and also lead to a splitting of the bark, affected parts becoming progressively dry and enventually dying.

[R]Common Names
DE: Gemeine Kommaschildlaus ES: Serpeta del olmo FR: Cochenille virgule du pommier IT: Cocciniglia a virgola dell'Olmo e dei fruttiferi PT: Cochonilha vírgula da macieira GB: Oystershell scale, Muel scale

[R] Images

  1. Lepidosaphes ulmi (L.) (Coutin R. / OPIE)
    Colony of female individuals on apple Scales protect eggs during the winter.
  2. Lepidosaphes ulmi (L.) (Bénassy C. / INRA Antibes)
    Damage on olive Fruits are covered with scales.
  3. Lepidosaphes ulmi (L.) (Bénassy C. / INRA Antibes)
    Males and females on olive
  4. Lepidosaphes ulmi (L.) (Bénassy C. / INRA Antibes)
    Live female on olive
  5. Lepidosaphes ulmi (L.) Schematic drawing of female clutch (in Arambourg (Entomologie oléïcole))

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