Ground Pearls Information
Species & Identification
The name “ground pearl” refers to several species of scale insects that live in the soil. They receive their common name from the wax cysts or “pearls” that nymphs produce to envelop their bodies. The cysts are spherical, about 1/8 inch in diameter or smaller, and pearl white to yellowish in color. The ground pearl species that affect turfgrass in South Carolina is the pink ground pearl, Eumargarodes laingi. When they become adults, females emerge from the cysts and crawl around to lay eggs. Adult females are about 1.16 inch long, have a soft body, and are pink in color.
Damage & Symptoms
Ground pearls feed by sucking sap from the roots of turfgrass. They feed on all turf and weedy grass species, but they are most damaging on centipedegrass. Turfgrasses can often tolerate feeding from a small population of ground pearls. However, root systems become increasingly compromised and damage becomes increasingly apparent as the population grows over several years. Initial above‑ground symptoms are irregularly shaped patches of thinning and chlorotic turfgrass. These patches turn brown in the summer and die in the winter but do not recover in the spring. The thinned or bare patches expand as damage continues. Ground pearl damage is easily confused with drought stress, grub damage, or nematode damage. Soil should be sampled and carefully examined to detect ground pearls and confirm infestation.
Life Cycle
Little is known about the biology of ground pearls. Ground pearls are believed to have one generation per year, but it is likely that some nymphs may take more than one year to complete development when host plant quality is poor or when environmental conditions are not suitable for nymph development or adult emergence. Ground pearls overwinter as nymphs in cysts attached to roots. Adult female emergence typically occurs in April through July. Adult females then move around in the soil or the thatch for about one week, during which they lay eggs in the soil (about 1 to 4 inches deep) over a two‑week period. Each female will lay about 100 eggs in ovisacs (a sac made of wax deposits to contain and protect eggs) during this time. Eggs hatch in about 9 to 15 days. Since adult emergence and egg laying span a long period, eggs can continue hatching until the end of August. Crawlers emerge from the eggs and attach to root tissue; once attached, they excrete a waxy coating or cyst that completely envelops and protects them while they feed, develop, and overwinter.
Scouting
Since the above‑ground symptoms of an infestation can be confused with other environmental stresses or diseases, ground pearl infestation must be confirmed with soil sampling. Sampling should be conducted in areas where the grass is thinning and yellowing—where the highest numbers of ground pearls may reside. Do not sample in areas where grass has already died. Ground pearls are not distributed evenly in a lawn; therefore, multiple samples should be collected from different spots. Soil samples should be taken to a depth of 4 inches; ground pearls can be found as deep as 12 inches in sandy soil. Break up the soil cores to locate the pearly white cysts.
Cultural Control
The most effective cultural control approach is to promote grass growth in order to mask or recover from damage by ground pearls. Adhere to best management practices for your turfgrass species or cultivar. To help promote plant recovery in centipedegrass lawns, increase mowing height, provide adequate irrigation, and avoid over-fertilization. In other turfgrass species, increasing nitrogen fertilization and providing adequate irrigation may help promote recovery, while sufficient soil potassium can encourage rooting. If feasible, consider replacing centipedegrass with other turfgrass species or cultivars that tolerate ground pearl infestations better, such as bermudagrass or zoysiagrass. Converting turf to ornamental landscape is also an option.
Chemical Control
Currently, no insecticide has been registered or shown to be effective in controlling ground pearls or reducing their damage. There is evidence that broad‑spectrum insecticides, such as carbaryl, organophosphates, and pyrethroids, may reduce the natural enemies of ground pearls, potentially worsening infestations.
| Category | Details |
|---|---|
| Species & Identification | Ground pearls are scale insects that live in the soil, producing wax cysts for protection. The pink ground pearl (Eumargarodes laingi) affects turfgrass in South Carolina. Nymphs form pearl-like cysts that are white to yellowish, about 1/8 inch in diameter. Adult females emerge to lay eggs and are pink in color. |
| Damage & Symptoms | Ground pearls suck sap from turfgrass roots, primarily damaging centipedegrass. Early symptoms include irregular thinning and yellowing patches, which turn brown in summer, die in winter, and fail to recover in spring. Damage can resemble drought stress or nematodes. Confirm infestation through soil sampling. |
| Life Cycle | Ground pearls have one generation per year but may take longer to develop in poor conditions. They overwinter as nymphs in cysts attached to roots. Adult females emerge between April and July, laying about 100 eggs 1-4 inches deep in the soil. Eggs hatch in 9-15 days, and crawlers attach to roots to feed and form protective cysts. Hatching can continue until late August. |
| Scouting | Infestations should be confirmed with soil sampling, especially in yellowing or thinning grass patches. Sampling should reach 4 inches deep but may extend to 12 inches in sandy soils. Collect multiple samples from various lawn spots and look for white cysts. |
| Cultural Control | To reduce damage, promote turf growth using best management practices. For centipedegrass, increase mowing height, ensure proper irrigation, and avoid over-fertilization. Other turfgrasses benefit from increased nitrogen and potassium for root strengthening. Consider replacing centipedegrass with more resistant species like bermudagrass or zoysiagrass. |
| Chemical Control | No registered insecticides effectively control ground pearls. Some broad-spectrum insecticides (carbaryl, organophosphates, pyrethroids) may worsen infestations by killing natural enemies. |
