Pasture Webworm

Hednota species

Family: Pyralidae

Order: Lepidoptera

Description:

Adult

Colour - Grey to brown.

Body - Small. Stout with long hair scales. 10 mm long.

Wings - 2 Pairs. Membranous. Hairy. Fore wings may have white lines, are speckled, and are darker than hind wings.

Mouthparts -

Antennae - 3 segments. Filiform (Finely hair like).

Legs - Broad overlapping scales. Feet (Tarsi) have 5 segments.

Head - Smooth. Broad overlapping scales. Large rounded compound eyes.

Thorax - Broad overlapping scales. 3 segments. Front segment much smaller. Hairy

Abdomen - Broad overlapping scales. 7-11 segments. Spiracles on segments 1-7. Hairy

Egg - Flat. Oval.

Habits - Can't fly when cold. Attracted to lights.

Caterpillar -

Colour - Pale to dark brown. Translucent.

Body - Cylindrical. 15 mm long.

Mouthparts - Chewing.

Antennae - Short. 3 segments.

Legs - 5 segments. Single claw on end.

Head - Hard.

Thorax - 3 pairs of legs.

Abdomen - 10-11 segments. Spiracles on segments 1 to 8. Prolegs on segments 3, 6 and 10.

Habits - Herbivorous. Live in web lined tunnels on leaves or underground. Only emerge from tunnels when cool and damp - usually at night. Prefers grasses.

Biology:

Life Cycle:

The moths lay eggs on grasses in the autumn. These hatch and the caterpillars burrow into the soil and make web lined tunnels. They feed through out winter then go into a resting stage in their tunnels for the spring and summer. They pupate in late summer and emerge in autumn often in very large numbers that swarm around lights.

Habitats:

Prefers grasses.

Origin and History:

Distribution:

Significance:

Caterpillars cut cereal and grass plants at ground level and may pull the plant down into its hole or leave it scattered on the surface. They are a major pest of cereals and pastures.

Management and Control:

Insecticides are used for control in cereals and pastures.

Cultivation to form a 3 week fallow usually provides good control. Infestations are usually worse under minimum tillage, grassy and cool moist situations. They are usually not a problem in stubble paddocks.

Thresholds:

Cereals - Spray at the first sign of damage and within 3 weeks of emergence.

Inspect crops every 4 days after planting especially if conditions are dry.

Oats are rarely affected.

Related Species:

Cabbage Centre Grub (Crocidolomia binotalis), Cucumber Moth (Diaphania indica), Wax moths (Galleria mellonella and Achroia grisella), Rice moth (Corcyra cephalonica), Meal moth (Pyralis farinalis)

Similar Species:

References:

CSIRO. The Insects of Australia. Melbourne University Press. (1991) p887.

WADA. Insects and Allied Pests of Extensive Farming. Department of Agriculture - Western Australia Bulletin No. 4185. p48.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.