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Icerya purchasi (Maskell)
Pericerya purchasi

Insecta, Homoptera, Margarodidae .

Australian mealybug, Fluted scale

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

- Adult: female (pseudo-female) brick red, thus coloured by its blood-red haemolymph. Antennae: 11 segments; two pairs of abdominal spiracles. Antennae and legs are dark brown to black.
Body oval, carinate, with median thoracic protruberences covered with a light brown, waxy secretion and white wax, with a thin waxy fringe (*) .
At the end of growth, the female secretes a characteristic, pure white ovisac from the ventral surface of the abdomen with 16 longitudinal grooves, the length of which may be longer than the body (about 5 mm) (*) .
- Male: yellowish in colour, with brown antennae, mesothorax and legs, wings (1 pair) smoky grey, 3 mm long, developing from a larva protected by a white, waxy scale; 8 mm long and 2 mm wide.
- Egg: oval, reddish.
- Nymph: red on hatching, flattened and oval in shape (0.5 mm long) with 6 long posterior setae; .antennae with 6 segments.
Shortly after hatching, the nymphs become covered with a white waxy coating. They secrete long, fragile, waxy anal tubes, which transmit the drops of honeydew excreted from the anus (*) .

- This scale insect is polyphagous, with a prediliction for Citrus, Pittosporum, broom (Genista), acacias, false acacia (Robinia), etc. It may also attack herbaceous plants.
- Hermaphrodite species; the female is capable of self-fertilization. Fertilized eggs produce females.
Unfertilized eggs produce males. The latter are rare and have little or no role in reproduction.
- Each female lays 600 to 800 eggs.
- The life-cycle lasts a minimum of 3 months.

[R]Life Cycle
The fluted scale produces 2 or 3 generations each year. Overwintering occurs in all instars, but mostly as an N3 nymph. Starting in February, each female may lay 400 to 800 eggs, on Citrus or other evergreen plants. Later hatchings (and the corresponding "waves " of mobile nymphs) occur in June and September.

- Damage caused by this scale insect is always very severe in the case of major infestation: sucking of sap, bark lesions, deformity and weeping constitute direct damage; the abundant production of honeydew on which sooty moulds develop (indirect damage) aggravates the situation.
Because it has no enemies, this scale insect develops on Citrus fruit trees and gives them the appearance of being covered with snow (*) . Production is gravely affected and the trees die.

Originating from Australia, this species has spread through all tropical and subtropical regions and glasshouses in colder countries. It appeared in California in 1868, and shortly before 1900 (date when it was reported from Naples) in Portugal.
Acclimatization of the Australian
ladybird Rodolia (Novius) cardinalis (*) to the United States, then Europe and North Africa gave the first and most famous success in biological control. Since then, Icerya purchasi has rarely been seen to be deleterious.

[R]Common Names
DE: Australische Wollschildlaus ES: Cochinilla acanalada, Cochinilla australiana FR: Cochenille australienne IT: Grande cocciniglia cotonosa degli agrumi PT: IcÚria GB: Fluted scale, Australian mealybug

[R] Images

  1. Icerya purchasi Maskell (Coutin R. / OPIE)
    Females and nymphs on acacia
  2. Icerya purchasi Maskell (Coutin R. / OPIE)
    Female laying eggs Eggs are regrouped in the ovisac.
  3. Icerya purchasi Maskell (Coutin R. / OPIE)
    Young nymphs on leaf
  4. Icerya purchasi Maskell (INRA / Antibes)
    Novius (Rodolia) cardinalis Originating from Australia, this ladybird was introduced at the end of the 19th century to be used as a beneficial insect in biological control. It feeds on all stages of this scale insect.
  5. Icerya purchasi Maskell Colony on orange twig (Bernard J.-F. / INRA Maroc)

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