Larinus minutus

BIOLOGY: Adults are active from May to September. They are 4 to 5 mm long. Females produce 30-130 eggs in their lifetime. Up to 5 eggs are deposited in the flower head of each knapweed plant. Larvae hatch in 3 days and then spend 4 weeks in the seed head before pupating. Pupation takes 1 week. Adults drop off of plants in September and overwinter in the soil.

DESTRUCTIVE STAGE: Larvae (feeding on seed head) and adult (leaf and seed feeding)

IMPACT TO HOST: Damage can reduce stand density and provide excellent control. L. minutus will be most effective when released with other knapweed biological control agents.

REDISTRIBUTION: Adult L. minutus can be collected using a sweep net or by picking them off of plants in June and July. A typical release is 150-250 adult insects.

SPECIES OF KNAPWEED ATTACKED: Diffuse knapweed, spotted knapweed, squarrose knapweed.

  • SCIENTIFIC NAME: Larinus minutus
  • COMMON NAME: Lesser knapweed flower weevil
  • TYPE OF AGENT: Insect: Beetle (Coleoptera: Curculionidae)
  • GENERATIONS PER YEAR: One
  • OVERWINTERING STAGE: Adult (in soil)
Larinus minutus
Larinus minutus

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