Carpet-Grass Webworm Moth

This handsome little fellow is demonstrating a “downward dog” position.

The carpet-grass webworm moth (Fissicrambus haytiellus) is a nondescript moth in the family Crambidae, which includes grass moths. “Grass moths” fold themselves up like the photo above when at rest to blend in with grass stems. (It does not work as well when the moth is resting on stucco.)

I seem to have found a relatively dark brown individual; generally these tiny, tubular moths are light brown or yellow, with that broad, white longitudinal stripe being very distinctive.

The adult moths do not damage grass, but the larvae can. Larvae of webworm moths spend the night feeding on grass stems and leaves near the soil, and spend the day hiding in burrows lined with silk (hence the name “webworm”). Enough larvae feeding in an area can produce ragged brown spots in the grass, or even kill grass that’s already under pressure from summer heat and drought.

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