Monday, 6 June 2016

Bertha armyworm monitoring

This week on the Farm: Bertha Armyworm (Mamestra configurata)

The past few days we have been very busy setting up Bertha Army Worm traps.  Bertha Armyworm adults will begin to emerge from their overwintering pupa around early June and will continue until early August. The number of adults collected by a trap will provide an indication of the risk of larval damage.

When setting up a monitoring site for Bertha Armyworm, it is important that the traps are not placed next to a shelterbelt, ditch, or within ½ a kilometer of a strong light source. Each trap should be located about 2 m from the edge of the field.  In the Peace River region, previous trapping has resulted in high numbers of native Bombus species so only one trap is deployed per site.

The traps used to monitor Bertha Armyworm are called Unitraps. The trap is all green and is mounted  approximately 1metre above the ground on a strong stake (Figure 1). Inside the trap, a pheromone lure is positioned to attracts male moths into the bucket then a Vapona insecticide strip within the bottom of the trap kills the males once they are inside the bucket.

Figure 1. Unitrap mounted on stake within a field
(photo source:

Our Bertha armyworm traps are collected weekly.  To do so, the Unitrap is opened, the contents are carefully emptied into a small brown paper bag which is labelled then stapled shut. The sample is taken back to the lab where the moths and by-catch are sorted and typically the specimens are pinned and labelled.  

Presently, non-automated traps are used.  However, because Bertha Armyworm moths are active at dusk, our lab has tested automated pheromone traps that remain closed during the day to reduce by-catch of Bombus species.  That automated traps were designed to remain closed during the day but automatically open in the evening to attract and intercept bertha armyworm males during peak flight times.

For more information on Bertha Armyworms follow the link to the protocol: