Asparagus Beetle
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Treat, then re-check in 5–7 days
Pick off the worst material, apply the organic option below, and look again after five to seven days. If the spread continued, escalate rather than repeating the same treatment.
Carried by insects
An insect moves it plant to plant, so controlling the carrier matters as much as treating the symptom. Check for the vector before assuming the plants infected each other directly.
Safe to compost
No pathogen carries over on this material, so it can go on an ordinary heap with the rest of the garden waste.
When and where to look
Scout the planting while temperatures hold between 12°C and 30°C.
The signs that lead here
Full problem lists for these crops
About
Asparagus beetle (Crioceris asparagi) is a black-and-cream beetle with red margins that feeds only on asparagus. Damage to the summer ferns matters more than damage to the spears, because the ferns are what build the crown for next year’s crop.
Symptoms
Rows of small dark eggs standing on end along the spears and fern needles. Adults and grey slug-like larvae strip the fern to bare stems, which turn brown, and spears become bent and scarred.
Organic Treatment
Pick beetles and larvae off by hand into soapy water, morning and evening through May and June, and rub the eggs off the spears as you harvest. Cut spears frequently during the cutting season — it removes the egg-laying sites.
Chemical Treatment
Pyrethrum controls both adults and larvae but has a short harvest interval, and repeat treatment through the summer is usually needed. Not required in most gardens where hand-picking is done consistently.
Prevention
Cut down and burn the ferns in late autumn — the adults overwinter in hollow stems and surrounding debris. Keep the bed weed-free and avoid leaving old fern lying near the crowns.
Crops at risk
Related problems
Asparagus Beetle risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.