Ground Pearls
Margarodes spp., Margarodidae, HEMIPTERA


DESCRIPTION

Adult -- About 1.6 mm long, the adult female is a pinkish scale insect with well-developed forelegs and claws. The male is a gnat-like insect varying from 1 to 8 mm in length.

Egg -- Clusters of pinkish-white eggs are enveloped in a white waxy sac.

Nymph -- Commonly referred to as a ground pearl, the slender nymph is covered with a hard, globular, yellowish-purple shell. An encysted nymph varies from 0.5 to 2.0 mm in diameter.


BIOLOGY

Distribution -- Ground pearls are potentially serious problems in both southeastern and southwestern states.

Host Plants -- The roots of Bermuda, St. Augustine, zoysia, and centipede grasses are most commonly infested with ground pearls.

Damage -- The ground pearl nymphs extract juices from underground plant parts. The damage is most apparent during dry spells when irregularly shaped patches of grass turn yellow. The grass in these spots eventually turns brown and usually dies by fall.

Life History -- Overwintering takes place in the ground pearl stage. Females usually reach maturity in late spring and emerge from their cysts. After a brief period of mobility, the wingless females settle 5 to 7.5 cm deep in the soil and secrete a waxy coat. Within this protective covering, females develop eggs (without mating) and deposit them throughout early summer. Approximately 100 eggs are laid by each female. The slender nymphs emerge in mid-summer and infest grass rootlets. Once they initiate feeding, nymphs soon develop the familiar globular appearance. There is usually one generation each year. However, if conditions are not favorable for emergence, female nymphs may remain in the ground pearl stage for several years.


CONTROL

Insecticides have not been effective against ground pearls. Good cultural practices, such as watering and fertilization may help lawn grasses recover from injury, but such beneficial effects may be only temporary. For recommendations, consult the state agricultural extension service.