Insect Pests of Fruit, Plantation, Medicinal & Aromatic Crops (2+1)

1. Green Scale

1. Green Scale - Coccus viridis (Coccidae: Homoptera)

• Green scale is an important sucking pest of Arabica, but attacks robusta also.
Life history

• The adult scale is flat, oval, light green with an irregular dark distinct loop on the middle of the dorsum.
• The adult is sedentary and spends its whole life in one place, it lays 50-60 eggs.
• The duration of the life cycle is 4-6 weeks.
• Adult lives up to 2-5 months.
Damage

• The scale attacks tender parts, setting down on the underside of the leaves close to midrib, veins, and tips of green shoots.
• The continuous sucking results in excess loss of sap from the plant which leads to debilitation of the older plants and death of nursery plants.
• The honey dew secreted by the scale forms a film on the leaves and a black fungus (sooty mould) grows on it, which hinders photosynthesis.


Ant association

• Association of ants with green scale is similar to that explained for mealybugs.
Control measures

• Maintain optimum shade
• Control ants by dusting quinalphos 1.5% or methyl parathion 2% or malathion 5% dust around the base of the bush and shade trees. Destroy ant nests.
• Remove and destroy weeds, as many of them harbor the pest.
• Use recommended dose of insecticide when the attack is above ETL.