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Pest Information

Annual bluegrass weevil

Annual bluegrass weevil

  • Latin Name: Listronotus maculicollis
  • Common Name: Annual bluegrass weevil
  • Other Names: Turfgrass weevil, Hyperodes weevil (a previous genus name)

Pest Details

Origin:

This is a native insect in the northeastern United States, and now found in the southeastern Provinces of Canada.

Biology:

This beetle tends to feed only on short-cut annual bluegrass, and therefore is a serious pest on golf course turf. If the turf is kept at a height of 1.5 inches or higher the beetle is not a significant problem. Both adults and larvae feed on the grass blades, but only the larvae do serious damage, feeding within the stems of the grass initially but then dropping to the soil to feed on roots and crowns of the grass. Adult beetles overwinter in protected places adjacent to the turf, emerging in the spring to invade the turf and deposit eggs. Typically there will be 2 generations each year, but 3 generations are possible in warmer regions.

Identification:

Adult beetles are only 3-4 mm long and very dark brown to black. Their snout is relatively short and the antennae arise from the end of the snout, rather than the base as in many other weevils. They are cylindrical and the sides of the abdomen are parallel. Larvae are legless and white with a black head and the body is curved only slightly if at all, distinguishing them from the curved, C-shaped white grub larvae. The mature larva is only the size of a grain of rice.

Characteristicts Important to Control:

Typically control targets the emerging adult beetles in the spring in an effort to kill the adults before they deposit eggs. Treatment is needed only where annual bluegrass is present in the turf, and contact residual insecticides will be effective. The adult beetles will be in the thatch area and the insecticide needs to be irrigated to move it down into the thatch.

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