Temperature is a key driver of insect development.
A mild August in Australia means that some areas are likely experiencing earlier than usual Etiella moth activity.
Keep a close watch on susceptible crops with the SARDI Etiella degree-day model and a sweep net.
What is Etiella?
Etiella or the lucerne seed web moth are the common names for the moth Etiella behrii.
As the weather warms up in September and October, these adult moths begin to emerge from their pupal stage after overwintering from the previous Autumn. Female moths will then lay their eggs on developing pods, stems and flowers in susceptible legume crops, particularly lentils.
Within 24 hours of hatching, the immature larvae will burrow into the pods, where they will feast and fatten themselves up on the developing grain.
Sheltered inside the pod, they are also protected from insecticides.
The larvae won’t emerge from the pods until they are ready to pupate in the soil. By then, the damage to the developing grain has already been done. The key to protecting your crops from Etiella damage is to target moths before they lay eggs.
Forecasting Etiella activity
Timing is everything when managing this pest.
To support monitoring efforts and to help achieve a well-timed spray, use the SARDI Etiella degree-day model.
The model uses local temperature data from 21 June onwards to forecast the flight activity of Etiella moth.
Once the degree-day accumulations hit 351, we can expect about 10% of their flight activity to have begun.
It is recommended that monitoring begins at 300 degree-day accumulations.
What to expect in 2024
This year, some areas are likely experiencing earlier moth flights compared to 2023, due to a warmer August.
For example, this season, Swan Hill exceeded 300-degree days 11 days earlier than 2023 (figure 1). Elmore and Horsham are also on track for slightly earlier moth flights than last year (figures 2 & 3).
However, not all regions may be experiencing earlier flights. In Wagga Wagga, for example, when comparing 2023 and 2024 there was only one day difference at 300-degree day accumulations.
For further instructions and to run the model for your location, visit:
How to monitor for Etiella
Use a sweep net to monitor for Etiella moths at least once a week while crops are green (dry crops aren’t at risk). A minimum of 3 sets of 20 sweeps should be randomly undertaken within each crop.
The recommended threshold is 1-2 Etiella moths in 20 sweeps.
For more information see the Lucerne seed web moth Pestnote.
Cover image: Photo by Cathy Powers, CC BY 4.0
