There is a particular kind of centipede lawn failure we see across the sandy ground of Jefferson County: a patch goes yellow in summer, browns off, and expands a little each year, and no amount of water, fertilizer or fungicide does anything. Dig under the edge of it and sift the soil. If you find tiny, hard, yellowish beads clinging to the roots, you have ground pearls.
What ground pearls are
Ground pearls are scale insects that live entirely underground. The immature stage secretes a hard, waxy shell around itself, which is the "pearl": a sphere about the size of a grain of sand up to a small BB, off-white to yellow or pinkish. Inside that shell the insect feeds on grass roots for a year or more. Adults emerge briefly in late spring to lay eggs at the edge of the infestation, which is why the patches spread outward slowly.
They feed on all warm-season grasses but centipede is the most sensitive by far, and in this region centipede on sandy soil is where almost every infestation we find lives.
What the damage looks like
- Irregular patches of yellowing turf in summer, turning brown by late summer or fall.
- Patches that expand a few inches to a foot a year, roughly circular, often merging.
- Grass that is loose and thin at the edge of the patch, with weeds moving into the center.
- No obvious insects at the surface and no fungal pattern. Insecticide and fungicide applications make no difference.
- Damage that is worst in dry, stressful years and seems to ease in wet ones.
It looks a lot like centipede decline, nematode damage, or chronic drought stress, which is why it goes undiagnosed. The pearls are the only way to be sure.
How to confirm
At the edge of a patch, where dying grass meets living, dig a spade-width hole about six inches deep. Break the soil up over a piece of white paper or a tray and look closely, or rinse a handful of soil through a kitchen sieve. The pearls are small but distinct, and if the infestation is significant you will find several in a shovelful. Check two or three spots. Your county extension office can confirm a sample.
The hard truth about control
There is no insecticide that reliably controls ground pearls in home lawns. The waxy shell protects the feeding stage, they live too deep for surface treatments to reach, and nothing is currently labeled that solves the problem. Products sold for grubs or chinch bugs do not work on them. Anyone who tells you a spray will fix it is guessing.
What you can do is manage the lawn so the grass outgrows the feeding, which is a real strategy and works well enough on lightly infested lawns.
Managing around them
- Reduce every other stress. Ground pearls kill stressed centipede, not healthy centipede. Correct watering, correct height and correct feeding matter more here than anywhere.
- Water deep and infrequent so roots go below the feeding zone. Frequent shallow watering keeps roots exactly where the pearls are.
- Mow high, two inches for centipede, and never scalp.
- Feed lightly. Pushing centipede with nitrogen to "help it recover" causes decline on top of the pearl damage. Potassium and iron are safer choices; see iron versus nitrogen.
- Fix pH if a soil test shows it high. Centipede under pH stress has less tolerance for anything else.
- Build organic matter on sandy ground with compost topdressing, which improves water holding and root depth over time.
When to change the grass
On a heavily infested lawn, the practical answer is sometimes to stop growing centipede in that area. Bermuda and Zoysia tolerate ground pearls better than centipede does, and both can be sodded into the affected areas. St. Augustine is intermediate. In heavy shade where none of those will grow, a bed or groundcover ends the problem entirely. Our guide to choosing a grass type covers the trade-offs, and when to renovate helps with the decision.
Do not spread them
Ground pearls move in soil. Do not move soil, plugs or sod from an infested area to a clean one, and clean equipment that has been digging in a bad patch before using it elsewhere. They spread slowly on their own; do not help.
FAQ
Will the patches ever go away on their own?
Not usually. They expand slowly for years. Management slows them and lets healthy turf hold ground.
Are ground pearls the same as grubs?
No. Grubs are beetle larvae, are much larger, and are controllable. Ground pearls are scale insects with no practical control.
Could it be nematodes instead?
It could, and the two often occur together on sand. Nematodes need a lab assay to confirm. Our nematode guide covers that.
Can you help manage an infested lawn?
Yes. Height, watering and feeding are what we control every week; see our services.
If your centipede is dying in expanding patches and nothing has helped, get in touch and we'll dig and look. We maintain centipede lawns across the sandy ground around Lamont, Wacissa and the rest of the county.