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Ministry of Agriculture, Food and Rural Affairs

european fruit scale

European fruit scale on limb (BC Ministry of Agriculture and Lands) European fruit scale on fruit (BC Ministry of Agriculture and Lands)
Click to enlarge.

Beginner

Scientific Name
Quadraspidiotus ostreaeformis (Curtis)

Identification
Nymphs (crawlers):

  • Bright yellow with long antennae.

Adults:

  • Females are immobile and covered with a circular waxy coating that is elevated at the centre.
  • Males are 1.3 mm in size, brownish red with an elongated abdomen, long antennae and wings.

Damage:

  • Young scales produce a large quantity of honeydew – a clear, sweet liquid serving as a medium for fungal growth.
  • Scale causes round spots on bark and weakens trees.
  • Scale appears as spots encircled by a red halo on leaves and fruit.

Often Confused With

Period of Activity
Mated and fertilized females overwinter as immature scales on twigs. Overwintering young begin to develop in adult females – located beneath thick waxy scale coverings – in May and June. Scales suck sap from leaves and twigs in July and August. Winged males appear in August, and die after mating with females. 

Scouting Notes
Monitoring for scale should be conducted in orchards with a history of damage from this pest. Monitor fruit at harvest for scale. Use black electrical tape (with adhesive side out) around the scaffold limbs of trees, in areas with known infestations, to detect crawler activity. Place bands in trees by mid June for 7-10 days after petal fall and replace every two to three weeks throughout the season. Crawlers yellow bodies will be caught on the tape.

Thresholds
It is rarely distributed uniformly throughout a tree, and may only infest a few trees in the block.  Monitor for scale during pruning or on fruit at harvest. Use black electrical tape (with adhesive side out) around the scaffold limbs of trees, in areas with known infestations, to detect crawler activity. Place bands in trees by mid June for 7-10 days after petal fall and replace every two to three weeks throughout the season. Crawlers yellow bodies will be caught on the tape.

Advanced

Scientific Name
Quadraspidiotus ostreaeformis

Identification
Crawlers (nymphs) are bright yellow with long antennae. Females are immobile and covered with a circular waxy coating that is elevated at the centre. Adult males are 1.3 mm in size, brownish red with an elongated abdomen, long antennae and wings. 

Scales suck sap from leaves and twigs in July and August. Young scales produce a large quantity of honeydew – a clear, sweet liquid serving as a medium for fungal growth. Scale causes round spots on bark and weakens trees. Scale appears as spots encircled by a red halo on leaves and fruit. 

Often Confused With

Biology
Mated and fertilized females overwinter as immature scales on twigs. Overwintering young begin to develop in adult females – located beneath thick waxy scale coverings – in May and June. Females give birth to live young. Crawlers move to the undersides of leaves, twigs and scaffold limbs to settle and feed. Wood older than three years is usually too thick for insect mouthparts to penetrate. Winged males appear in August, and die after mating with females.  European fruit scale has a limited host range and infests primarily Malus (apple) spp., Pyrus (pear) spp. and Prunus (tender fruit) spp. There is one generation of this pest each year.

Period of Activity
Scales suck sap from leaves and twigs in July and August.

Scouting Notes
Monitoring for scale should be conducted in orchards with a history of damage from this pest. Monitor fruit at harvest for scale. Use black electrical tape (with adhesive side out) around the scaffold limbs of trees, in areas with known infestations, to detect crawler activity. Place bands in trees by mid June for 7-10 days after petal fall and replace every two to three weeks throughout the season. Crawlers yellow bodies will be caught on the tape.

Thresholds
It is rarely distributed uniformly throughout a tree, and may only infest a few trees in the block. Monitor for scale during pruning or on fruit at harvest. Use black electrical tape (with adhesive side out) around the scaffold limbs of trees, in areas with known infestations, to detect crawler activity. Place bands in trees by mid June for 7-10 days after petal fall and replace every two to three weeks throughout the season. Crawlers yellow bodies will be caught on the tape.

Management Notes

    • Crawlers spread through orchards by wind, birds’ feet, workers’ clothing and on farm equipment.
    • Successful scale insect control starts with prevention.
    • Carefully examine all nursery trees prior to actual planting. If scale insects are present, discard trees or exchange for clean trees.
    • Plant new orchards away from hardwood stands and from older plantings where scale has been a problem.
    • For established orchards with a history of scale problems, use Superior oil before the tree breaks dormancy when scales have only a thin wax covering.
    • Delaying application until green tissue is present often results in poor scale control, because scales have produced a larger protective wax coating making complete coverage of the insect more difficult.
    • For more information on the timing of products for managing scale, see OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :
      • Recommendations for European fruit scale at Dormant.