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Ministry of Agriculture, Food and Rural Affairs

European apple sawfly

Mature European apple sawfly larva Adult European apple sawfly (Dr. Charles Vincent, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, QC) Typical sawfly injury at harvest Young fruitlets injured by sawfly larval feeding White sticky 3D trap used to monitor adult sawflies Lathrolestes ensator female (Dr. Charles Vincent, AAFC, Saint-Jean-sur Richelieu, QC)
Click to enlarge.

Beginner

Scientific Name
Hoplocampa testudinea        

Identification
Eggs:

  • 0.8 mm long,
  • Shiny,
  • Oval,
  • Transparent.

Larvae:

  • Five larval instars,
  • 1st instar
    • 1.7 mm in length,
    • Light cream coloured with a black head and caudal (rear) shield.
  • 5th instar
    • 9-11 mm long,
    • Head and shield have become pale brown in colour.

Adults:

  • 7-8 mm long,
  • Light orange to yellow head, antennae, lower body and legs,
  • Upper body is dark brown and shiny,
  • Female slightly larger than the male.

Damage:

  • First instar larval feeding creates a heavily russetted, winding, ribbon-like scar that spirals out from the calyx seen on mature fruit at harvest,
  • Second instar larval feeding creates exit holes on fruit with reddish-brown frass protruding, causes fruit to abort and/or creates scars on the fruit.
  • As the larvae matures and feeds internally, it enlarges its exit hole with wet, reddish-brown frass on the side of the fruit.
  • Damaged fruit drops during the “June drop” period.

Often Confused With

  • Codling moth and appleworm larvae- Similar in appearance but can be distinguished by the number or prolegs (five). 
  • Codling moth damage- European sawfly damage appears in orchards sooner (2-3 weeks after petal fall), as compared to codling moth damage which does not appear until five or more weeks after petal fall.
  • Tarnished plant bug damage- Tunnelling scars from first instar larvae are similar to damage caused by the tarnished plant bug.

Period of Activity
Adults are active from pink through petal fall. Fruit damage occurs two to three weeks after petal fall

Scouting Notes
Monitor European apple sawfly using 3D visual traps consisting of non-UV white sticky boards that mimic blossoms. Three traps are placed in trees between tight cluster and pink, and remain in the orchard until two weeks after petal fall. They are positioned ideally on the south side of the tree at eye level and along edges of the orchard bordering woodlots or fence rows. The traps are checked for adult sawflies twice a week.

Thresholds
The action thresholds for post-bloom timing are:

  • Six European apple sawfly per trap if a pre-bloom insecticide has been applied;
  • Three European apple sawfly per trap if no pre-bloom insecticide has been applied.

Advanced

Scientific Name
Hoplocampa testudinea        

Identification
Eggs are 0.8 mm long, shiny, oval and transparent. Newly hatched larvae measure about 1.7 mm in length and are light cream coloured with a black head and caudal (rear) shield. There are five larval instars. By the time larvae reach the mature fifth instar, they are 9-11 mm long, and their head and shield have become pale brown in colour. The adult is 7-8 mm long with light orange to yellow head, antennae, lower body and legs – the upper body is dark brown and shiny. The female is slightly larger than the male.

First instar larvae feed beneath the fruit skin and create a heavily russetted, winding, ribbon-like scar that spirals out from the calyx end. If larva ceases feeding at this early stage, for whatever reason, this damage will likely be seen on mature fruit at harvest. If this tunneling stops early, tunneling scars are short and indistinguishable from damage caused by the tarnished plant bug.

Second instar larvae tunnel into fruit towards the seed cavity. Reddish-brown frass is often seen protruding from an exit hole in fruit. Larval feeding into the core of the apple often causes fruit to abort, while sub-surface feeding creates scars visible on the fruit at harvest.

As the larva molts and matures, it moves towards the seed cavity or adjacent fruit. As the larva feeds internally, it enlarges its exit hole with wet, reddish-brown frass on the side of the fruit. The larva moves to other fruit in the cluster to continue feeding. A single larva can damage several apples. Damaged fruit drops during the “June drop” period.

Often Confused With

  • Codling moth and appleworm larvae- Similar in appearance but can be distinguished by the number or prolegs (five). 
  • Codling moth damage- European sawfly damage appears in orchards sooner (2-3 weeks after petal fall), as compared to codling moth damage which does not appear until five or more weeks after petal fall.
  • Tarnished plant bug damage- Tunnelling scars from first instar larvae are similar to damage caused by the tarnished plant bug.

Biology
European apple sawfly overwinters as a mature larva in a cocoon a few centimetres below the soil surface. The larva pupates in the spring and adults emerge during the pink stage of apples. The female European apple sawfly lays eggs just after the king flower opens. Eggs are deposited singly at the calyx end of the flower, often at the base of or between the stamens. After 8-10 days, newly hatched larva burrow into the apple and feed on tissue just below the skin. As the larva matures, it tunnels deeper into the seed cavity and feeds on one or two seeds. Larvae often move between developing fruitlets. Larva matures in four to six weeks, then leave the fruit (which has usually dropped), burrow into the soil and form a cocoon in preparation for pupation. There is one generation per year. Diapause may last for up to three years.

Period of Activity
Adults are active from pink through petal fall. Fruit damage occurs two to three weeks after petal fall

Scouting Notes
Monitor European apple sawfly using 3D visual traps consisting of non-UV white sticky boards that mimic blossoms. Three traps are placed in trees between tight cluster and pink, and remain in the orchard until two weeks after petal fall. They are positioned ideally on the south side of the tree at eye level and along edges of the orchard bordering woodlots or fence rows. The traps are checked for adult sawflies twice a week.

Thresholds
The action thresholds for post-bloom timing are:

  • Six European apple sawfly per trap if a pre-bloom insecticide has been applied;
  • Three European apple sawfly per trap if no pre-bloom insecticide has been applied.

Management Notes

  • There are two times when European apple sawfly can be controlled with an insecticide:
    • pre-bloom – adult European apple sawfly are usually controlled by broad-spectrum insecticide applied at pink to control tentiform leafminer or spring-feeding caterpillars;
    • post-bloom – shortly after bloom, young, newly hatched larvae of European apple sawfly are controlled by application of an insecticide. This is the most effective timing for controlling this pest and it is important not to delay this application.
  • European apple sawfly has no known natural enemies in North America. Researchers from Agriculture and Agri-Food Canada are studying introducing a larval parasite Lathrolestes ensator (Brauns) into Quebec and eastern Ontario orchards. This is not a stand alone method of control but is used in conjunction with reduced-risk pesticides and cultural methods to reduce the population of European apple sawfly.
  • For a list of the products available to manage European apple sawfly, refer to OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :