Dingy cutworm (Feltia jaculifera)

Dingy cutworm biology & life cycle

Dingy cutworm can be found across the Prairie provinces. This cutworm is primarily a leaf feeder, and rarely cuts plants. Visible damage is more likely as lost foliage or gaps in the field.

Dingy cutworms overwinter in their larval stage. As a result, they will appear larger in the spring, than other cutworm species that overwinter in their egg stage.

Identifying Dingy cutworm

Dingy cutworm: larvae

The larvae of dingy cutworms have a thin light line down the middle of the back. On either side of this thin line there is a broader series of somewhat diagonal markings that look like tire tracks, or to form "V's" on the back. They also have 4 equal-sized black dots on the back surface of each abdominal segment.
[Source: Canola Council ]

Dingy cutworm: Pupae

Dingy cutworm pupae are about 20 mm long and indistinguishable from other cutworm pupae.

Dingy cutworm: adult

The adult dingy cutworm wingspan is 30 to 40mm in length. The forewing is dark gray/brown to black with lighter hind wing.

Dingy cutworm: management

Watch for damaged plants in June and July. Cutworms are nocturnal and hide during the day, making detection difficult. Inspect seedlings every 3–4 days during the first few weeks of crop development.
Focus scouting activity on south-facing slopes and hilltops. Soils are warmer and soil texture tends to be lighter, which is conducive to cutworm feeding activity.

Scouting:

Observe: Look for bare areas, holes and notches in foliage, and plants that are wilting, toppling over or completely cut off.
Dig: When notched, wilted, dead or cut-off plants are seen, dig around the roots (up to 4" deep) for cutworms.
Act: The economic threshold is 25–30% stand reduction. Patch spraying may be sufficient if concentrated to small areas.

Outbreak factors include:

Spring:
Warm and dry spring weather can increase the severity of damage from cutworms.

Summer:
Very dry soil during the larval stage increase cutworm behaviour and feeding habits. A hot, dry August also provides the best conditions for adult moth feeding.

Fall:
Cutworm moths lay several hundred tiny eggs on or just below the surface of loose, dry soil where they can comfortably overwinter.

Manage preventatively with seed treatment insecticides registered for cutworm. Foliar insecticide treatments may be warranted if economic thresholds are exceeded.

The following Management Practices* are recommended:

Natural biological enemies like parasitic insects, viral diseases and bacterial infections increase after year two of an infection and can reduce populations for at least two years.
Minimum tillage creates a greater diversity of cutworm species, but also of the natural parasites that keep populations in check.
Delaying seeding by 10–14 days may help reduce populations by starving young larvae populations.
Weed control in fallow fields is critical in late summer when cutworms are laying eggs.

*Source: Canola Council of Canada.