Asparagus beetle infestations in a garden are a common problem for asparagus growers. The asparagus beetle is a small, oval-shaped insect that feeds on the shoots, leaves, and stems of asparagus plants. Infestations can lead to reduced growth and yields, as well as unsightly damage to the plants.
Symptoms
- Yellow or brown discoloration on asparagus fronds
- Fronds that appear shriveled, curled, or distorted
- Holes or missing chunks on shoots and stems
- Yellow or brown spots on leaves
- Black or brown excrement on leaves or stems
- Presence of asparagus beetles or their eggs on the plants
What is an Asparagus Beetle
Adults
- Oval-shaped body
- Approximately 1/4 inch in length
- Black head and thorax
- Rusty-red wing covers
- Six black spots on wing covers
Larvae
- Pale yellow and plump
- Approximately 1/2 inch in length
- C-shaped grubs
- Found feeding on asparagus fronds and stems.
Eggs
- Small and oval
- Light yellow or yellow-orange in color
- Usually found on the upper surface of asparagus leaves and stems
- Clumped together in groups of 10 to 20 eggs
- Typically hatch into larvae within a week of being laid.
Treating an Asparagus Beetle Infestation
Hand picking
- Inspect plants regularly and remove adult beetles, eggs, and larvae by hand
- Drop them into a bucket of soapy water to kill them
Insecticide application
- Apply insecticides such as carbaryl, permethrin, or spinosad to kill adult beetles and larvae
- Follow label instructions and use protective equipment
- Monitor plants after application to ensure effectiveness
Crop management
- Clean up and destroy any asparagus debris after harvest to reduce overwintering sites for beetles
- Plant asparagus in well-drained soil with good air circulation to discourage infestations
Natural predators
- Encourage populations of natural predators such as lady beetles, lacewings, and parasitic wasps to help control asparagus beetle populations
- Avoid using insecticides that may harm natural predators