It can be soil Mealy bugs, sometimes it is called "Blind Mealy Bugs" it measure about 1/16 inch. Because they are white or light gray in color, they often resemble small grains of rice. Soil Mealy Bugs feed on the roots of African Violets, particularly the new feeder roots in the upper layer of the soil. The resulting damage stifles the ability of roots to absorb water and nutrients. First, isolate the affected plants, especially if they share a common watering tray with other, healthy plants. Although Soil Mealy Bugs do not spread easily, they will travel over moist surfaces. To treat for Soil Mealy Bugs, you will have to repot your African Violet in a soil that has been mixed with Diatomaceous Earth. Use about 1 tablespoon per one liter of soil. Pasteurize soil before repotting. To make soil uninhabitable for future Mealy Bug infestations, mix about 1/4 tablespoon of Diatomaceous Earth with every liter of soil.