Ground pearls

A subterranean scale insect (Margarodes spp.) of warm-season turf, recognized less by the insect than by slowly enlarging circular-to-irregular dead patches in bermudagrass, centipedegrass, and zoysiagrass. Digging at the patch margin and sifting soil reveals the diagnostic 'pearls' — hard, globular, yellowish-to-purplish encysted nymphs up to about 1/16 inch in diameter clinging to roots; adult females are wingless, pinkish, about 1/16 inch with stout clawed forelegs.

Roughly circular patches of yellowing turf that thin and die out, slowly enlarging over seasons and failing to recover with irrigation or fertility; affected areas are most obvious during summer drought because root feeding limits water and nutrient uptake, and the patches tend to reappear in the same spots year after year.

Ground pearls are root-feeding scales in the family Margarodidae with a long, poorly synchronized life cycle. Eggs are laid in spring within a waxy sac; mobile first-instar 'crawlers' settle on roots and secrete the hard protective cyst (the pearl) in which they overwinter and may persist for one to two years or longer. Adult females typically become active in late spring and early summer. The protective cyst makes most stages effectively immune to soil insecticides.

Damage is favored by sandy, well-drained soils in the warmer parts of the southern U.S. and is most evident during summer heat and drought stress, when weakened turf cannot mask the root injury. Decline appears as enlarging thin or dead patches, often persisting and recurring in the same area for years.