Ground Pearl

Ground pearl is the common name for a group of scale insects in the family Margarodidae that live in the soil and feed on grass roots. They get their name from the pearl-like cysts the immature nymphs form around themselves, which are small, round to oval, pinkish to purplish or straw-coloured, and about 1 to 2.5 millimetres across. These cysts are made of a hardened waxy secretion and are often mistaken for tiny beads, seeds, or even soil particles when dug from the root zone.

The adult female is a small, soft-bodied, wingless insect that stays below ground and rarely leaves the pearl cyst except to lay eggs nearby in the soil. Adult males are tiny, winged, and short-lived, appearing above ground only briefly to mate. The nymphs, which do most of the damage, insert long sucking mouthparts into grass roots and stay attached for extended periods while encased in their pearl-like shell, effectively cutting off the root's ability to take up water and nutrients.

In Australia, ground pearl is mostly a problem in warm-season turf, particularly buffalo, couch and zoysia lawns in warmer coastal and inland regions where soils stay warm for much of the year. It tends to be more persistent in sandy or well-drained soils and becomes more noticeable during hot, dry periods when the turf is already under moisture stress and cannot compensate for the reduced root function.

There is no simple curative treatment once an infestation is established, as the cysts are protected underground and can persist for a long time. Management is mostly about supporting turf health and growth to help it tolerate the root damage: maintaining consistent but not excessive irrigation, avoiding close mowing that stresses the plant further, and applying balanced fertiliser to encourage new root growth. Badly affected areas sometimes need renovation or reestablishment with new turf, since ground pearl can persist in soil for years even after grass is removed.