Pasture tunnel moth

As the coldest months begin, keep a look out for pasture tunnel moth ‘soil chimneys’ in pastures and crops coming out of pastures

The grey-brown body of pasture tunnel moth larva (Source: cesar)

 

Where have they been reported?

Pasture tunnel moth (Philobota productella) larvae appear to be responsible for widespread damage in late sown canola at a property near Wodonga in Victoria’s North East district. The pasture tunnel moth larvae have chewed the leaves off at stem level and strewn them all over the ground. The most heavily affected paddock came out of pasture last year, reflecting the pasture tunnel moth’s preferred habitat. In this case, signature chimney-like structures protruding up from the soil surface (classic signs of pasture tunnel moth larvae) were not seen, but they may have collapsed or been washed away after recent rains.

About the pasture tunnel moth

Pasture tunnel moths are native to Australia. They are normally found in higher rainfall districts and can cause significant damage to annual and perennial grasses, and clovers. They have also been recorded damaging wheat and barley crops in the past, although this is the first report of pasture tunnel moths in canola that we have had.

The larvae have a slender, grey-brown coloured body that makes them very inconspicuous in the soil. They have a black head, grow up to 35 mm long and have several long sparse setae (stout hairs) around the head. Larvae hide within vertical, silk-lined tunnels during the day, emerging at night to feed nearby on crop or pasture plants, often dragging leaves back into their tunnels to feed. Adult moths are elongate, glistening white-cream in colour, around 20 mm long and have a wingspan of approximately 25 mm.

Pasture tunnel moth larvae can be distinguished from pasture webworm by their slender size and the absence of webbing on leaves. Pasture tunnel moth tunnels are silk lined, and have an above-ground ‘chimney’, whereas pasture webworm tunnels have only an opening at ground level.

Our advice

Most damage by larvae of pasture tunnel moths occurs in July and August, and is often associated with blackheaded pasture cockchafers. Paddocks should be inspected now and throughout winter for signs of lopped leaves and formation of chimneys or silk-lined burrows. 

There are no chemicals registered for the control of pasture tunnel moth. Some growers have reported that similar products and rates used against blackheaded pasture cockchafers have provided satisfactory control.

 

Sources of field reports of pasture tunnel moths

David Eksteen – Agronomist, Agricultural Consulting (North East Victoria)