Tiny Flies on New Sod: Harmless Adults, Watch for Larvae

Small flies swarming new sod worry a parent with young children. Are they harmful? Should you spray?

Adult Flies = Nuisance, Not Damage

Flies and moths on turf don't eat grass. But females lay eggs that hatch into larvae (caterpillars, grubs) which do feed on blades or roots.

Identify Now, Treat Later

• Catch a few flies/moths; note size, color, wing pattern.
• Research their life cycle to predict larval emergence.
• Target treatment at the vulnerable larval stage—not adults.

Child-Safe Option: Bacillus thuringiensis (Bt)

Bt strains target only caterpillars (lepidopteran larvae) or specific grubs (e.g., B. thuringiensis subsp. galleriae for beetle grubs). Harmless to humans, pets, bees. Apply when larvae are young and actively feeding.

Don't spray blindly. Monitor, identify, and treat precisely with biologicals for safety and efficacy.