Chinch bugs are the most common St. Augustine pest in Williamson County, and their damage looks almost exactly like drought stress. If your Georgetown lawn is yellowing in patches despite adequate watering, chinch bugs are the first thing to check — before you turn the sprinklers up and make it worse.
When to check: the June window
According to Williamson County AgriLife Extension, the primary chinch-bug check window in this area is June 1 through June 15, as temperatures climb and the bugs become active. Damage typically shows up first in the hottest, sunniest parts of the lawn — along driveways, sidewalks, and south-facing slopes where the soil heats up most.
How to confirm it: the coffee-can test
The coffee-can test is the standard AgriLife method and takes five minutes. Remove both ends of a metal coffee can, push it two to three inches into the soil at the edge of a yellowing patch — right where green grass meets the stressed area — and fill it with water. If chinch bugs are present, they float to the surface within a few minutes. A count of 25 or more bugs per square foot crosses the treatment threshold.
Yellowing despite adequate irrigation is the key indicator of chinch bugs in St. Augustine. More water makes it worse, not better.
How to treat it
Insecticides with the active ingredients bifenthrin (sold as Talstar) or cyfluthrin (Tempo) are effective against chinch bugs. Treat in the early morning when temperatures are lower, and follow the product label exactly. Rotate the site-of-action class between treatments to avoid building resistance. Stop irrigating the affected area while you treat — the bugs thrive in the hot, dry stress the lawn is already under.
Chinch bugs vs. fungal disease
If the patches appear after heavy rain or wet periods rather than in dry heat, suspect fungal disease (large patch or brown patch) instead — common in Williamson County clay that drains slowly. Fungal damage tends to form rings; chinch-bug damage spreads as irregular, expanding yellow-to-brown patches in full sun. An operator with lawn-treatment capability, not just mowing, can tell the difference and apply the right product.
Not sure which grass you have, or whether the damage is pests or drought? Start with the grass-types guide, then request a match with a local operator who treats lawns in your neighborhood.