Cassava (Manihot esculenta Crantz) is an important tuber crop grown for food, feed and beverages. Because of its ability to grow on soil of low organic content and produce high yield, it is considered a food security crop in African countries. Now it became the industrial crop since it is raw material for the production of starch, energy and live stock feed. In Tamil Nadu, it is grown in Salem, Namakkal, Erode, Cuddalore, Dharmapuri and Kanyakumari districts, both in irrigated and rainfed condition. Recently , the major constraint in cassava production are mealybug damage. The invasive mealybug species, Phenococcus manihoti Matile-Ferrero (Pseudococcidae) was first reported from Salem district and its occurrence was found associated with other species of mealybug. The nymphs and adult of mealybugs were collected from farmer”s field in Namakkal, Salem and Tiruppur district and morphological characters were observed to identify the key characters of mealybug species. Among the specimens collected, the species identified with colour, wax coating and body filaments were Ferrisia virgata, Pseudococcus jackbeardsleyi and P. manihoti. P. manihotidifferentiated from the other species with its distinct symptom of distortion of leaves at tip (Bunchy top) and extensive honey dew secretion.