Lucerne seed wasp

Lucerne seed wasp, Bruchophagus roddi, adult wasp showing clear, rounded wings
Adult lucerne seed wasp. Photo: L Turton
Lucerne seed wasp, Bruchophagus roddi, larva
Larvae. Photo: L Turton

Scientific name

Bruchophagus roddi


Adult wasps are shiny black with clear wings and dark brown legs. Wasps lay a single egg into the soft young seed. Minute, white, legless larvae develop and pupate inside the seed.

Similar species

Green vegetable bug egg parasite. Seed damage is unlikely to be confused with any other lucerne seed eater.


Europe and west Asia, North and South America, Australia. In Australia, the lucerne seed wasp has been reported as a lucerne pest in New South Wales, Queensland, South Australia, Victoria, and Western Australia.

Pest status

Major - damage more severe in southern growing areas - irregular.

Crops attacked



Seed is hollowed out by larvae. Damaged seed does not germinate and are dull brown, dark brown or almost black.

Risk period

Late summer, particularly for crops grown for seed. Maturing pods are not susceptible to damage.

Life cycle

Adult wasps emerge in spring and lay eggs through the young, soft pod into the soft seed. Once injected into the seed, the egg hatches to a larva which eats out the seed contents and pupates in the hollow seed. A single adult emerges from the seed by chewing a small, circular hole with jagged margins. In summer all stages of the wasp can be found in the field at any one time. In autumn, the pre-pupae enter a winter diapause in the seed until the following spring.


Usually most active in spring. Adult wasps can be detected in crops by sweep-netting. Immature stages can be detected by pulling apart pods and examining seeds with a hand lens.

Action level

Any immature lucerne seed wasp detected in the crop destined to be harvested for seed is likely to result in economic loss. Preventative control is necessary in areas with a history of damage by lucerne seed wasp.


Chemical control is only effective against adults. Since emergence is continuous during summer, repeated spraying may induce secondary insects and may not be cost effective. Sprays for other pests may incidentally reduce numbers of lucerne seed wasp adults. For chemical control options see Pest Genie or APVMA.  

Cultural control is the most important control method.

  • Early seed harvest reduces the chance of damage from wasp populations, which peak in summer. Uniformity of crop flowering reduces the number of late set pods.
  • The removal of volunteer lucerne from roadsides, headlands and irrigation banks, cutting adjacent non-seed crops for hay and removal of hay before the seed matures may reduce reservoirs of the wasp. Prevent seeding of uncut lucerne by heavy stocking.
  • Reduce winter carry over of the wasp by harvesting before pods begin to shatter and by cleaning harvested seed and burning all seed cleanings or seed fumigation. Cultivation of the crop during autumn or winter, so that the seed is buried at least 5 cm, may also reduce overwintering populations.
Plant resistance

Seed damage by lucerne seed wasp to lucerne lines with tightly coiled pods is reported as being less than those with more open pods.

Further information

Last updated 10 November 2010