Asparagus Beetle

• Small black beetles with creamy yellow spots, or orange beetles with black spots, on asparagus spears and foliage
• Chewing damage on emerging spears — scarring, notching, or disfigured tips
• Dark brown-green larvae feeding on ferns; small dark egg clusters laid lengthwise on spears
• Fern damage later in the season reduces root reserves and next year's crop
• Poor shipping-quality spears with visible scarring

Two species attack asparagus: the common asparagus beetle (Crioceris asparagi — black with cream spots) and the spotted asparagus beetle (C. duodecimpunctata — orange with black spots). Adults overwinter in plant debris and emerge as the first spears push up. Females lay dark eggs lengthwise on spears (common) or on fern foliage (spotted). Larvae feed on ferns, pupate in the soil, and produce 2–3 generations per year. Population builds across the season if left unchecked.

1. 01Harvest daily during peak spear production — removing spears also removes eggs
2. 02Hand-pick adults in the morning when they are sluggish; drop into soapy water
3. 03Remove and dispose of all fern debris in fall — destroys overwintering habitat
4. 04Encourage natural enemies: ladybugs, lacewings, and parasitic wasps (Tetrastichus asparagi) keep populations in check
5. 05Spray neem oil or spinosad on fern foliage if defoliation is severe; time applications when larvae are present
6. 06Avoid broad-spectrum insecticides — they kill the natural predators that keep asparagus beetles suppressed

If you're losing significant crown vigor year over year despite hand-picking, contact your extension office — they can confirm which species is dominant and advise on regionally appropriate biological control releases.

• Asparagus Beetles— University of Minnesota Extension
• Asparagus Beetle— Penn State Extension