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Mytilococcus beckii (Newman)
Lepidosaphes beckii

Insecta, Homoptera, Diaspididae .

Citrus mussel scale

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

- Adult female: covered by a convex pyriform scale, frequently elongated and arched like a comma; general colour grey, lighter on the margins. Dimensions: 2.5 x 1.0 mm (*) .
The female found under the scale has a pyriform nacreous-white body with a yellowish pygidial spot. Later on the body becomes yellow all over (Dim.: 1,00 x 0.61 mm). The female has piercing-sucking mouthparts.
- Adult male: The scale covering the male insect is smaller (Dim.: 1,3 x 0.4 mm) with straight margins and is the same colour as the female one. Male insects have wings and resemble minute midges. They have no mouthparts and show a general pink-violet colour (Dim.: 0.54 x 0.20 mm).
- Eggs: ellipsoidal. However, when together they form subparallel masses.
- Nymphs: 1st- and 2nd-instar nymphs precede the emergence of adults, male forms occurring only after a quiescent period.

The typical host plants are those of the genus Citrus (*) .
- Each adult female after mating lays an average of 70 eggs in her life-time.

[R]Life Cycle
A first generation starts in November in southern Portugal where most citrus orchards can be found. This first generation has a winter diapause. The second generation begins by the end of June and a third one appears from September onwards.

This insect sucks the tree sap through its piercing-sucking mouthparts, the attack being more serious on the leaves (*) , young twigs and fruits. Respiration and photosynthesis are impaired by the excessive amount of scales covering the attacked tissue as the dead ones remain attached to the plant.
This scale does not excrete honeydew and consequently no sooty moulds develop.
Young attacked fruits lose weight and become smaller and may even drop off in case of an early attack. When Mytilococcus beckii attacks fruits during the summer or autumn months the fruit maturation as well as its quality are affected (*) .
Attacked fruits are discoloured and scale scars remain even after the removal of the scales by brushing in the packing line.

[R]Common Names
DE: Zitrus-Kommalaus ES: Serpeta gruesa FR: Cochenille virgule des citrus IT: Cocciniglia a virgula degli agrumi PT: Cochonilha vírgula GB: Citrus mussel scale

[R] Images

  1. Mytilicoccus beckii (Newman) (BASF)
    Colony on orange
  2. Mytilicoccus beckii (Newman) (BASF)
    Females on leaf of citrus
  3. Mytilicoccus beckii (Newman) (BASF)
    Pullulation under leaf of citrus
  4. Mytilicoccus beckii (Newman) (Bénassy C. / INRA Antibes)
    Ventral side of female
  5. Mytilicoccus beckii (Newman) (Bénassy C. / INRA Antibes)
    Damage on lemon
  6. Mytilicoccus beckii (Newman) Colony of Lepidosaphes glowerii on a leaf (Bernard J.-F. / INRA Maroc)

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