Clover Root Weevil - identification

Adults.

Clover root weevil (Sitona lepidus).

  • Mahogany brown.
  • Narrow head region.
  • Most noticeable in summer.
  • Capable of flying.
  • Feeds exclusively on clover.
  • 4-6 mm.

Irenimus (I.compressus & I. aequalis)

  • Two common pasture species look similar.
  • Pale margin on tip of abdomen.
  • Broad head and blunt snout.
  • Feeds on a variety of plants, including plantain & clover.
  • Not a serious pasture pest. Native to NZ.
  • 4-7 mm.

Whitedfringed weevil (Naupactus leucoloma)

  • Light-dark grey or brown.
  • White band along side of body.
  • Flightless.
  • Feeds on a variety of plants, preferring legumes.
  • Large: 10-12 mm.

Argentine stem weevil (Listronotus bonariensis)

  •  Grey colour.
  • Curved snout.
  •  Serious pest of ryegrass.
  • Small: 2-3 mm.

Lucerne weevil (Sitona discoideus)

  • Light coloured body.
  • Black stripes behind eyes.
  • Pale furrow in centre of forehead.
  • Short snout.
  • Serious pest of lucerne.
  • 4-5 mm.

Larvae.

Clover root weevil (Sitona lepidus)

  • North Island, Canterbury and Nelson
  • Seen in spring & autumn under clover plants.
  • Brown head region.
  • No legs.
  • Creamy-beige colour.
  • 1-6 mm long.

Whitefringed weevil (Naupactus leucoloma)

  • North Island & most of South Island.
  • Seen throughout year, but particularly autumn.
  • Fatter than CRW and a bright white colour.
  • Pale head is tucked into body so often only black mouthparts are visible.
  • No legs.
  • Distinctly C-shaped.
  • 12-15 mm long when mature.

Black beetle (Heteronychus arator)

  • North Island only.
  • Seen in spring.
  • Tan head.
  • Note the orange-brown legs.
  • 30 mm long when mature.

Grass grub (Costelytra zealandica)

  • North & South Island, though rare in Northland.
  • Seen in Feb-March & Sept-Oct.
  • Honey-brown head & semi-translucent body.
  • Tail end is distinctly dark in colour.
  • Thrive in light, well-drained soils.
  • 20-25 mm long when mature.

Tasmanian grass grub (Aphodius tasmaniae)

  • North & South Island, especially coastal regions.
  • Seen in April, later than NZ grass grub.
  • Dark brown-black head distinguishes it from NZ grass grub larvae.
  • Feed on foliage of grasses, clover, lucerne and turf.
  • Damage characterised by bare patches of soil in autumn to late winter.
  • 15 mm long when mature.

Note: Many native South Island weevil larvae feed on roots. These look like CRW, but do not cause any problems in pasture. If you are uncertain of the identification, look for other signs of damage or contact an expert.