Northwest berry Foundation

Management Detail

Raspberry Beetle

in Raspberries

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Latin name: Byturus unicolor

Description:

Reason for Concern:
1) Economically important northern Washington and British Columbia.
2) Adult beetles reduce yield by feeding on unfolding leaves and blossom clusters.
3) Larvae feed within flowers and burrow between the core and the berry flesh.
4) They can be a contamination problem at harvest.

Identification/Symptoms:
Formerly called the Western Raspberry Fruitworm, the Raspberry Beetle is small and brown, eats holes in terminal leaves and devours blossoms often injuring plants. Adults are light brown, somewhat flattened, covered with short hairs, and about 1/6" long. They leave a distinct feeding pattern on the leaves. Larvae, about ¼” long, often adhere to picked fruit. They have short legs and are light yellow with a cross band of light brown on the back of each segment.

Life Cycle:
Adult beetles overwinter in soil, emerging in spring to feed on fruit buds and unfolding leaves. Females lay eggs in May on the base of the blossom buds or on green fruit. Larvae work and develop inside the fruit and the fleshy receptacle, often causing fruit to dry up. Some feed until harvest. Most larvae mature, leave the berry and drop to the ground where they enter the soil and pupate. Adults form in late summer and overwinter.

Links:

Scouting:

  • Watch for damage to unfolding leaves and developing flower buds.
  • A beating tray can be used to monitor adult fruitworm activity before and during bloom.
  • A new style of monitoring trap has recently been introduced that will increase the effectiveness of control strategies. Work in Washington has shown that beetles are attracted to non-ultraviolet white sticky traps. Traps such as the Rebell R Bianco are effective for monitoring beetle flight activity.
  • Locate traps along field edges near adjacent raspberry fields or areas of alternate Rubus hosts (e.g. blackberry, thimbleberry). However, there are no threshold levels established for determining if sprays are required.
  • Treatments are usually targeted at the adults pre-bloom to prevent larval damage and contamination later in the season.

 
Cultural Controls:

None listed at present.

 

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

images


photo by K. Gray


Raspberry beetle larvae - photographer unknown


Raspberry beetle damage - photo by K. Gray


Raspberry beetle damage - photo by T. Peerbolt


Raspberry beetle damage - photo by T. Peerbolt


Raspberry beetle damage - photo by K. Gray


Raspberry beetle trap - photo by T. Peerbolt

 

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