Northwest berry Foundation

Management Detail

Weevil, Clay Colored

in Raspberries

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Latin name: Otiorhynchus sinularis

Description:

Reason for Concern:
1) Damage in early spring by adult clay colored weevils feeding on unopened buds.
2) Damage is often mistaken for winter injury.
3) Larvae (grubs) feed on the roots and weaken cane growth.

Identification:
Larvae are white or pink, legless, "C" - shaped grubs that feed on roots most of summer and winter. Adults are flightless, hard-shelled beetles, with long, downward curved mouthparts and elbowed antennae, moderately sized (smaller than Black Vine weevils), and about 3/8” long with reddish legs.

Life Cycle:
Adults start to emerge from the soil in early spring and most have emerged by mid-June. Adults climb canes at night to feed on buds and new laterals. Because they are flightless, they spread relatively slowly in a raspberry field. Eggs are laid by mid-July and hatch into grubs that feed on roots through summer. There is one generation per year.

Links:

Scouting:

  • In early-mid April, begin taking 10 beating tray samples from several sites in the field (monitoring technique developed by Washington State University, Whatcom County Raspberry IPM Manual), and record the number found. This is most effective at night or on cool cloudy days as this is when weevils will stay in the foliage.
  • In late May, begin examining foliage for weevil feeding signs (notching of the leaf margins).
  • 1 or 2 weevils found for every 10 beating tray samples taken may warrant the consideration of a pre-harvest spray to target those weevils.
  • The Clay Covered Weevil has not been identified as doing economic injury in Oregon and Southwest Washington only in the northern growing regions. But it is present in the south and is a potential pest there also.

 
Cultural Controls:

None listed at present.

 

For information about chemical controls, check with our Pesticide Guide.

images


photo by J. Troubridge


Clay colored weevil damage - G. Menzies


Clay colored weevil damage - G. Menzies


photo by K. Gray


photo by J. Troubridge

 

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