Asparagus beetle on asparagus head

Asparagus spear infested with asparagus beetle.

Updated: April 27, 2021

Appearance

  • Common or striped asparagus beetle: This is the more common beetle feeding on asparagus spears and ferns. The adults have colorful orange and blue-black markings.
  • Spotted asparagus beetle: This beetle has orange wing covers with 12 spots. Mainly a pest of the older asparagus cultivars that produce berries (newer all-male hybrids produce no fruit) because the larvae feed on the berries.
 Adult spotted asparagus beetle. Credit:Whitney Cranshaw, Colorado State University, Bugwood.org
Adult spotted asparagus beetle. Credit:Whitney Cranshaw, Colorado State University, Bugwood.org

Life cycle and habits

  • The ¼ inch long adults emerge from overwintering sites in and around the garden in early spring and feed on emerging spears.
  • There are multiple generations each year and populations can reach high levels leading to severe loss of spears and foliage.

Signs and symptoms

  • After mating, very small black eggs are inserted into the spears and the small gray larvae that emerge begin feeding on spears. 

Prevention and control

  • Handpick adults and larvae or control with a botanical insecticide (neem, pyrethrum).
  • Cut spears quickly after they reach eating size and clean up all plant debris and weeds at the end of the season to remove over-wintering sites.