PestFacts WA

Weevils and caterpillars can be sneaky

Pasture day moth caterpillars

  • Mullewa
Pasture day moth caterpillar.
Pasture day moth caterpillar. Photo courtesy of: Planfarm.

A Planfarm agronomist recently found pasture day moth caterpillars damaging a seedling wheat crop near Mullewa.

Pasture day moth larvae are dark brown with yellow and reddish orange markings. They have two prominent yellow spots near the end of the body and an orange-black head. Pasture day moth caterpillars remain on plants during the day.

Pasture day moth caterpillars are not usually considered a pest as they prefer to feed on capeweed, erodium and other broadleaved weeds.

Pasture day moth caterpillars are easily controlled by insecticides.

For more information pasture day moths refer to DPIRD’s Diagnosing pasture day moth damage page.

Canola weevils

  • Beverley
  • Boyup Brook
A canola plant with suspected weevil feeding damage
Canola plant with suspected weevil feeding damage. Photo courtesy of: Hilary Wittwer (Planfarm).

Hilary Wittwer (Planfarm) has found leaf damage to a 2-5 leaf canola crop west of Beverley. The culprit could not be found so pitfall traps have been put in the ground to see if weevils are present. There didn’t seem to be new damage to leaves which could indicate that that caterpillars have fed, pupated and emerged as moths and flown away.

Ben Creek (AGRIvise) has reported that vegetable weevils are damaging canola crops ranging from cotyledon to 7-8 leaf stage around Boyup Brook.

Vegetable weevils are about 10mm long with two short white stripes at an angle on each side of its abdomen. They are often camouflaged amongst stubble and trash and tend to hide during the day. Sections of cotyledons or leaves missing (often in patches) are a good indication of weevils or small caterpillars.

They may be confused with two other common weevil pests of crops and pastures: the spotted vegetable weevil (or desiantha weevil; 5mm) and the small lucerne weevil (10mm). Importantly, the vegetable weevil requires higher rates of insecticides than most pests of canola. For more information see DPIRD’s 2019 Autumn Winter Insecticide Guide.

For more information on weevils visit DPIRD's Diagnosing weevils in canola page.

Tools to help diagnose insects in crops

If you can manage to find an insect while inspecting a damaged area of crop and you are not sure what it is use the free PestFax Reporter app and take some photos, attach them to your report and request a diagnosis or select unknown for the pest. The PestFax team wants to know what invertebrate insects you are finding in your crops and pastures, whether it is a pest, beneficial or unknown. We even want reports of the usual insects that are seen every season.

You can also consider trying the free, easy to use grain pest identification field guide for Android and iPhone devices called MyPestGuide Crops. The app quickly identifies crop pests by filtering information on the damage or pest description and runs outside mobile range. There is also an app for identification of crop diseases called MyPestGuide Diseases.

For more information contact Dusty Severtson, Development Officer, Northam on +61 (0)8 9690 2160 or Alan Lord, Technical Officer, South Perth on +61 (0)8 9368 3758.