Brown or Pink Cutworm

Agrotis difficilis, Agrotis infusa, Agrotis munda & other species

Family: Noctuidae

Order: Lepidoptera

Description:

Adult

Night flying moths with eyes that reflect orange light. Attracted to lights.

Colour - Brown or grey.

Body - Medium size. Stout. Long hair scales.

Wings - 2 Pairs. Membranous. Hairy. Patterned. Wing-span 40 mm. Front wings are darker than hind wings which may be almost white.

Mouthparts -

Antennae - 3 segments.

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

Head - Broad overlapping scales. Large rounded compound eyes. Hairy unlashed 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 - Oblong. Often laid in clusters in a gel.

Habits - Can't fly when cold.

Caterpillar -

Colour - Grey green with a pink tinge.

Body - Smooth and plump. Up to 50 mm long.

Mouthparts - Chewing.

Antennae - Short. 3 segments.

Legs - 5 segments. Single claw on end.

Head - Hard.

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

Abdomen -

Habits - Herbivorous. Curls up when disturbed. Usually found on sandy soils. Feed at night and bury themselves during the day close to damaged plants.

Pupa -

Biology:

Life Cycle:

Moth flies by night and lays several hundred eggs on plants or the soil. These hatch in 4-7 days. Caterpillars live for around 4 weeks and remain close to where eggs were laid. Pupate in the soil at a depth of 15-75 mm. There may be several generations per year.

Habitats:

Origin and History:

Distribution:

Significance:

Caterpillar is a major pest of cereals, grasses and lupins that cuts the plant off just above the surface. 2-3 caterpillars can cut off all plants in a square metre. Lupins are most susceptible to damage from emergence to the 4 leaf stage. In lupins, they cut off portions of the leaf or cotyledons or cut through the stem just above ground level. Plants may survive moderate damage to the leaves or cotyledons but will die if the stem is cut.

Management and Control:

Biological control by fungi, wasps and flies often prevent outbreaks.

Insecticides provide reliable control for outbreaks.

Thresholds:

Thresholds:

Cereals - 4 large larvae per metre of crop row.

Canola - 4 large larvae per metre of crop row.

Lupins - Less than one larva per square metre for young crops. Check for damage to young leaves and cotyledons and for stems being cut just above ground level. They rarely cause economic damage after the crop has reached the 4 leaf stage.

Check the crop early and regularly for any sign of plants being cut off. Larvae can be difficult to find because they are often underground.

Related Species:

Armyworm, Bogong moth, Cluster caterpillar, Common Armyworm, Corn Earworm, Cutworms, Helicoverpa or Heliothis, Inland Armyworm, Loopers, Native budworm, Southern Armyworm.

Similar Species:

References:

CSIRO. The Insects of Australia. Melbourne University Press. (1991) p914.

WADA. Insects and Allied Pests of Extensive Farming. Department of Agriculture - Western Australia Bulletin No. 4185. p50.

Acknowledgments:

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