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Aonidiella aurantii (Maskell)
Aspidiotus aurantii, Chrysomphalus aurantii

Insecta, Homoptera, .

California red scale

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

- Adult: the female scale is brownish-red, circular, 1.8 mm in diameter. nymphal exuviae are little or not excentric, central or sub-central.
The female's body colour may be mistaken for that of the scale, under which it is visible. It remains elongate until the last stage, when it becomes kidney-shaped.
A characteristic, complete, whitish, ventral coating isolates the body of the female from the plant.
The male hymphal scale, oval and darker than the female, measures 0.8 to 1.2 mm; nymphal exuviae are excentric. The winged adult (1 pair of wings) is yellowish in colour (*) .
- Nymph: at first mobile (yellowish, 0.2 mm long) it then settles, taking on a circular form and secreting its scale (*) .

- Polyphagous species. Observed in Italy on Citrus, almond, vines, pear, plum jujube(Zizyphus), carob (Ceratonia) and rose (Rosa).
- Females secrete a pheromone. This attracts males, which emerge in the afternoon. Although they live for only one day, the males can move about 100 m upwind.
- Females are viviparous; eggs hatch just before being laid. Females produce 60 to 150 nymphs over a ten-day period.
- After a brief period of quiescence (2 to 4 hours), the nymphs leave the maternal scale and disperse on the host tree, preferably onto stems, but also onto foliage and fruits. The majority have settled one day later.
During the cold season, scale insects usually congregate on the sunnier parts of the foliage while, in the summer, they move to shadier zones. Reproduction is greatest during uniformly hot and dry conditions.
Summer heat, combined with even slight humidity, causes considerable mortality amongst newly emerged nymphs under the maternal scale.
- The imaginal moult usually occurs 6 to 6 weeks after egg hatch.

[R]Life Cycle
It is very difficult to distinguish between generations, which considerably overlap. Under favourable climatic conditions, there are four generations per year.
Overwintering takes place inall instars.
Viviparous females are active from the end of April to the first ten days of January; throughout this period, mobile nymphs are also found.
Settled N1 nymphs are also observed throughout the year except in April; N2 nymphs and young females are thus present at all times.

- The species is deleterious to Citrus. The presence of this scale insect weakens the infested organ and the plant itself by sucking the sap, causing therafter deformations by the action of toxic saliva.
Branches dry out and cortical lesions form, foliage yellows and falls, the fruits are encrusted with the scale insects which are very difficult to remove even by brushing in treatment systems (*) .

The following are important natural enemies: the fungus Cephalosporium lecanii,
predatory ladybirds (Chilocorus sp.) and parasitoid chalcid (Hymenoptera).
Amongst the latter, Aphytis melinus has been employed with success as a biological control agent against California red scale in Morocco.

[R]Common Names
DE: Rote Orangenschildlaus, Rote kalifornische Schildlaus ES: Piojo rojo de California FR: Pou de Californie IT: Cocciniglia rossa forte degli agrumi PT: Cochonilha vermelha dos citrinos GB: California red scale

[R] Images

  1. Aonidiella aurantii (Maskell) (Bénassy C. / INRA Antibes)
    Young stages on Citrus
  2. Aonidiella aurantii (Maskell) (Bénassy C. / INRA Antibes)
    Colony on orange
  3. Aonidiella aurantii (Maskell) Spring damage on lemon fruitlets (Bernard J.-F. / INRA Maroc)
  4. Aonidiella aurantii (Maskell) Late attack on an orange (Bernard J.-F. / INRA Maroc)

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