Insect
Asparagus Beetle
Distinctive black beetles 6 - 8 mm long with cream-and-red spotted wing cases, and their grey grubs, that strip asparagus foliage from spring through autumn.
Symptoms to Look For
- Foliage stripped from spears or fern, leaving bare stems
- Grey grubs up to 10 mm long on stems and leaves
- Spears scarred with dark feeding scars from adult beetles
Affected Plants
Asparagus
Organic Solutions
Hand-picking
Check plants daily from spear emergence and pick adults and grubs into soapy water - early intervention prevents severe defoliation.
Encourage natural enemies
Avoid disturbing ground beetles and parasitic wasps that prey on asparagus beetle larvae and pupae in the soil.
Prevention
- Clear and compost all fern growth in autumn to remove overwintering adult habitat
- Cultivate the soil around crowns in late winter to expose overwintering adults to frost and birds
Garden, by Willowbottom recommends only organic, wildlife-friendly solutions. No synthetic pesticides, no harmful chemicals - ever.