Red scale / Aonidiella aurantii

A dangerous pest of citrus crops, causes the fall of fruits and leaves, drying of whole plants.

Worldwide distributed tropical and subtropical species: Australia, Oceania, Africa, Nearctic (Mexico, USA), Neotropical (Argentina, Brazil, Galapagos Islands), Chile, Palearctic, Oriental region. It is imported with forage plants to many countries of the world, including Europe: Georgia (Abkhazia, Adjara), Spain, Italy, Cyprus, France.

Female produces 100 to 150 young altogether and live nymphs or crawlers emerge from under their mother's cover at the rate of two to three per day. When they first hatch the nymphs are a yellowish color and search for a suitable place to settle in depressions on twigs, leaves or fruits. They then start feeding by inserting their mouthparts deep into the plant tissue and sucking sap from the parenchyma cells. The saliva they inject is very toxic to the leaves, twigs, branches and fruit of citrus trees.

Although citrus is the main crop attacked by red scale, it can also be found on species from at least seventy-seven plant families.

Scale insects of all ages feed by sucking sap. They are found on all parts of the plant but are most noticeable on the fruit. Heavy infestations may cause discoloration, shoot distortion and leaf drop. The fruit may become pitted and unmarketable. The tree's bark may split and the twigs and branches may die back and this sometimes results in the death of the tree. Chemical control is difficult because the insects are protected by their hard waxy covers. They are also becoming resistant to many insecticides and indiscriminate use of pesticides has adverse effects on their natural predators.

The only mobile stage of red scale is the first instar crawler. It can move about a metre but may also be dispersed to other plants by wind, flying insects and birds as well as human activities.

Other crops that suffer economic damage from attack by red scale include papaya (Carica papaya) in Taiwan, guava (Psidium guajava) in India and olives in California and countries around the Mediterranean, with serious damage being caused to olives in Morocco.

SYNONYM:

Aonidia aurantii 

Aonidiella citri 

Aonidiella gennadi 

Aspidiotus aurantii 

Aspidiotus citri 

Aspidiotus coccineus 

Chrysomphalus aurantii 

Chrysomphalus citri