First signs of brown pasture looper activity

Sightings of brown pasture looper larvae typically occur from July onwards in south-eastern Australia.

 

The minor pest, brown pasture looper (Ciampa arietaria), generally becomes noticeable from July onwards. This species has an annual life cycle and produces one generation per year. Adult moths emerge from pupal cases and lay their eggs during autumn. Larvae hatch from the eggs and grow to full size in about two months. Once larvae reach full size in spring they pupate and remain dormant over summer.

True to its lifecycle, cesar recently identified some incidental brown pasture looper larvae that arrived in a sample of blue oat mite-impacted canola from the Forbes region of the Central West Slopes and Planes, NSW. Similarly, news from the twittersphere revealed a presence of the larvae in a canola paddock in the NSW Riverina.

The larval stage of brown pasture looper are relatively easy to identify once you know what to look for. The distinctive feature is two bright yellow, wavy lines running down along the back. Another key to identification are the ‘prolegs’. These are the fleshy, leg-like appendages that caterpillars use to move (the ‘prolegs’ are not to be confused with the three sets of thoracic ‘true legs’ that the brown pasture looper also sports near the head). While most caterpillars have four sets of abdominal prolegs, the brown pasture looper only has one set. They use their single pair of abdominal prolegs and one pair of anal prolegs to move using a series of back arches, which results in a characteristic looping motion.

To further confirm the identification of a suspected brown pasture looper, flip the grub onto its back or side and observe how many sets of abdominal prolegs it has.

 

Brown pasture looper larvae have one set of abdominal prolegs (Source: cesar).

 

While brown pasture looper is traditionally a minor pest, if crops (especially canola) have been slower to develop this season or are moisture-stressed, they will be more vulnerable to damage by larvae. Brown pasture looper larvae love to eat broadleaf weeds, particularly capeweed and storksbill, so paddocks with a history of these weeds may be at higher risk.

Crops attacked by brown pasture looper include canola, lucerne and lupins.

Control of brown pasture loopers can be assisted by natural enemies including parasitic wasps, which attack the eggs. They are also prey to spined predatory shield bugs and glossy shield bugs as young larvae. If chemical control is warranted, there are several insecticides registered against brown pasture loopers, however spot spaying or perimeter spraying is often all that is required.

Are you seeking further information on this species? Visit our comprehensive brown pasture looper PestNote.

 

Field oberservations

Tim Wright – AGnVET Services (Central West Slopes and Plains, NSW)