An early establishment pest, the weed web moth is also known as the cotton web spinner and web spinner caterpillar.

The weed web moth is a native species that can be found across much of arable Australia, but is most common in South Australia, Victoria and eastern New South Wales.

Key points

• The weed web moth (Achyra affinitalis) is a native moth present across much of the Australian cropping region, most commonly in South Australia, Victoria and New South Wales.
• It is a minor early establishment pest that rarely reaches high-enough numbers to cause economic damage in grains.
• Population numbers for this pest tend to be higher in years that are warmer than average and have early autumn rainfall.
• The larvae are most active in summer and can co-occur with several other lepidopteran larvae, which can be differentiated by their size, feeding behaviour and host preference.
• While there is limited information on this pest, beneficial species are likely to play a large role in their suppression. Therefore, if numbers are low, chemical control may not be required.
• If chemical management is required, be sure to check label rates and be aware that some labels use the name ‘web spinner caterpillar’ or ‘web spinner’.