Sunflower Moth

Symptoms by part

Causes

• Warm, dry weather conditions during the flowering stage.
• The presence of nearby wild sunflowers that act as a host reservoir.
• Planting sunflowers in areas where previous crops were infested and not cleared.

Could be confused with

• Bird damage · Birds typically leave large, jagged gaps in the seed head without the fine webbing or dark waste associated with moth larvae.
• Seed head rot · Fungal rot causes the flower head to turn mushy and dark, often with a foul smell, whereas moth damage is characterized by dry webbing and insect debris.

Treatment

1. 1. Cover the developing flower heads with fine mesh bags or cheesecloth as soon as the petals begin to unfurl to prevent egg laying.
2. 2. Apply Bacillus thuringiensis to the flower head surface at the very first sign of bloom to target young larvae before they tunnel deep.
3. 3. Remove and destroy any infested flower heads immediately to stop the larvae from maturing and dropping into the soil to overwinter.

Without chemicals

• Use fine mesh bags to physically exclude adult moths from the flower heads.
• Plant resistant sunflower varieties that have tighter, more protective bracts.
• Remove and dispose of all plant debris at the end of the season to eliminate overwintering sites.

Chemical options

• Bacillus thuringiensis, apply to the flower head surface during early bloom, follow the label.

Preventing it

• Rotate your planting site each year to avoid areas where larvae may have pupated in the soil.
• Clear away all wild sunflowers in the immediate vicinity to reduce the local moth population.
• Plant sunflowers at different times to ensure that not all your crops are at the vulnerable flowering stage simultaneously.

When to act

Act as soon as the flower buds appear by bagging them or applying treatments. If the majority of the seed head is already webbed and hollowed out, remove the entire head to prevent the larvae from completing their cycle.

Questions people ask

Can I still eat the seeds if I find moth damage?

If the damage is minor, you can often salvage the unaffected seeds by cleaning them thoroughly, but heavily infested heads with significant webbing and waste should be discarded.

Do these moths only attack sunflowers?

While they are most common on sunflowers, they can occasionally be found on related plants in the Asteraceae family.

Plants it affects

• Sunflower