Northwest berry Foundation

Management Detail

Weevil, Obscure Root

in Blackberries

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Latin name: Sciopithes obscurus


This species is part of the complex of a number of weevil species that are found in blackberries. It is usually not the predominant species, however they can contribute to serious economic losses as a weevil contaminant in harvested fruit. Control actions taken for Black Vine, Strawberry and Rough Strawberry root weevils will also control Obscure root weevils. One difference with this species is that it spends most of its time in the plant canopy and is less susceptible to the basal sprays than the other weevils. The adults appear after bloom, beginning in May and continuing through and after the harvest season. Control measures of the adults should be taken early prior to egg laying. Eggs that were laid in the soil prior to or during and after harvest will hatch into young larvae that then feed on roots.



  • 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.

Cultural Controls:

None listed at present.


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


photo by K. Gray

Obscure root weevil damage - photo by R. Rosetta

Obscure root weevil eggs - photo by K. Gray

photo by J. Boyd

Obscure root weevil damage - photo by K. Gray

Leaf knotching by obscure root weevil - photo by B. Leung


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