Chinch bugs
Tiny sap-sucking bugs that turn sunny patches of St. Augustine and other lawns yellow, then brown, in summer.
What you'll see
- Yellow patches that turn brown and die, starting in hot, sunny, dry spots and spreading outward.
- Tiny black adults with white wings, and red-orange young with a white band, in the thatch at the patch edge.
- Worst on St. Augustinegrass, and on lush, heavily fed or drought-stressed lawns.
Why it happens
Chinch bugs live in the thatch and suck sap from grass blades, injecting a toxin that yellows and kills them. Thick thatch, too much nitrogen and drought stress favor them.
How to fix it
- Confirm them: push a bottomless can into the turf at the edge of a yellow patch and fill it with water. Chinch bugs float up within minutes.
- Treat only if you find about 20 or more per square foot (30 by 30 cm). Use a product labeled for chinch bugs, and keep kids and pets off until it dries.
- Water deeply in dry spells, since stressed grass is damaged fastest.
Keep it from coming back
- Cut back on nitrogen fertilizer and keep the thatch layer thin.
- Where chinch bugs are common, ask about resistant St. Augustinegrass varieties.
- Check the sunny edges of the lawn often in summer.
Sources
General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.