---
title: Webworm
canonical: https://fernland.com.au/problem-solver/webworm/
dateModified: 2026-08-07 09:31:08
summary: "Webworm caterpillars shelter in silk-lined tunnels in thatch and feed on turf leaves at night, causing patchy browning in warm months."
type: article
keywords: [Webworm, Hednota spp.]
---

# Webworm

> Webworm caterpillars shelter in silk-lined tunnels in thatch and feed on turf leaves at night, causing patchy browning in warm months.

*Hednota spp.*

Webworm is the common name given to several native pasture moths of the genus *Hednota* (formerly grouped under *Hednota pedionoma* and related species) whose larvae damage turf and pasture grasses across Australia. The adult moth is small, greyish-brown to straw-coloured with narrow, folded wings and a snout-like projection at the front of the head, giving it a slender, elongated resting posture. Moths are mostly seen fluttering low over turf at dusk, especially after mowing or in the evening during warmer months.

The damaging stage is the larva, a caterpillar reaching around 15–20 mm at maturity, with a pale grey-brown to greenish body, a darker brown head and a row of faint spots along each segment. Larvae construct silken tunnels lined with chewed grass fragments and soil particles just below the thatch or soil surface, retreating into these shelters during the day and emerging at night to feed on leaf blades close to ground level.

Webworm is a recognised turf pest in warm-season grasses such as couch and kikuyu, but it can also affect cool-season species. Activity typically increases from late spring through summer and into early autumn when conditions are warm and larvae are actively feeding and developing. Populations can build quickly under favourable weather, particularly in well-fertilised, actively growing turf.

Management relies on regular monitoring during the risk period, since damage can appear suddenly once larvae reach later instars and feeding intensifies. Maintaining turf health through appropriate irrigation, mowing and fertility helps swards recover from low-level feeding, while heavier or persistent infestations may require a control program timed to target young larvae before they become well established in their silk tunnels.

## How to identify

- **Leaf damage:** ragged, notched or chewed grass blades, with closely grazed patches appearing as thinning or scalped-looking turf, most noticeable in the morning after overnight feeding.
- **Patchy browning:** irregular brown or thinned patches that can expand and merge under heavy infestation, sometimes resembling drought stress or disease.
- **Silk tunnels and frass:** fine silk threads binding grass clippings, soil and frass together at the thatch–soil interface; visible when thatch is parted or lifted.
- **Field check:** part the thatch or lift a small section of turf in affected areas during the day to look for caterpillars in their silken tunnels; a soap flush (mixing a small amount of dishwashing detergent in water and drenching a marked area) can also bring larvae to the surface within a few minutes if present.
- **Night inspection:** use a torch after dark to spot larvae actively feeding on leaf blades, which confirms current activity rather than old damage.
- **Lookalikes:** webworm damage can be confused with *armyworm* or *cutworm* feeding; armyworm larvae are typically larger, smooth-bodied caterpillars without silk tunnels, while cutworms shelter in soil burrows rather than silk-lined surface tunnels. Presence of the characteristic silk-and-soil tunnels is the clearest way to distinguish webworm.

## Registered products we stock

- [Syngenta Acelepryn GR | Professional Granular Insecticide | 4kg & 10kg](https://fernland.com.au/syngenta-acelepryn-gr-professional-granular-insecticide-4kg-10kg/) — Syngenta
- [AntStar 2G Bifenthrin Granular Insecticide](https://fernland.com.au/antstar-2g-bifenthrin-granular-insecticide/) — PCT SureFire
- [Fivestar Insecticide 80SC](https://fernland.com.au/fivestar-insecticide-80sc/) — PCT SureFire
- [Syngenta Acelepryn SC | Professional Liquid Turf Insecticide | 100ml to 5L](https://fernland.com.au/syngenta-acelepryn-sc-professional-liquid-turf-insecticide-100ml-to-5l/) — Syngenta
- [Biff 100SC Insecticide](https://fernland.com.au/biff-100sc-insecticide/) — Colin Campbell Chemicals
- [Tempo Xtra Turf & Ornamental Insecticide](https://fernland.com.au/tempo-xtra-turf-ornamental-insecticide/) — Envu
- [Venom Professional 240SC Insecticide](https://fernland.com.au/venom-professional-240sc-insecticide/) — Adama

## Image credits

- [Photo: dhobern via Wikimedia Commons (CC BY 2.0)](https://commons.wikimedia.org/wiki/File:Hednota_bivittella_1.jpg)
- [Photo: dhobern via Wikimedia Commons (CC BY 2.0)](https://commons.wikimedia.org/wiki/File:Hednota_pleniferellus.jpg)
- [Photo: dhobern via Wikimedia Commons (CC BY 2.0)](https://commons.wikimedia.org/wiki/File:Hednota_longipalpella.jpg)
- [Photo: Donald Hobern from Copenhagen, Denmark via Wikimedia Commons (CC BY 2.0)](https://commons.wikimedia.org/wiki/File:Hednota_pedionoma_(41824661521).jpg)