How to identify
- Adults with a red thorax and cream-and-black wing patches
- Dark larvae on spears and ferns
- Eggs stuck on spears like tiny black dashes
Damage: Scarred spears and defoliated ferns that weaken next year's crop.
Control methods
- Hand-pick adults and larvae in the morning.
- Harvest spears frequently so eggs and beetles have less time on the crop.
- Leave a few early spears as a trap crop, then destroy them.
What products to use
We list product types and what to check on the label — not brand rankings, prices, or “we tested” claims. Always follow the label for your crop, and prefer the least disruptive option that works.
Insecticidal soap or spinosad (labeled)
When: Heavy fern feeding after harvest ends
Look for: Asparagus beetle listed; protect pollinators on flowering ferns