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Ministry of Agriculture, Food and Rural Affairs

round-headed apple tree borer

Round-headed apple tree borer adult
Click to enlarge.

Beginner

Scientific Name
Saperda candida

Identification
Larvae:

  • Pale yellowish white,
  • Approximately 2.5 cm long,
  • Dark brown head and black mandibles.

Adults:

  • Light olive brown beetle with two conspicuous white stripes running the length of the body,
  • Length is just over 2 cm, and antennae are almost as long as the insect.

Damage:

  • Attacks healthy, living trees,
  • Larvae (grubs) feed on the cambial tissue and heartwood near the base of the tree by boring into the branches and the trunk,
  • Presence of larvae is indicated by sawdust castings pushed from the tunnel, accumulating on the ground beneath the tunnel entrance,
  • Girdling of young trees eventually results in a greatly weakened tree, often leading to death,

Often Confused With
N/A

Period of Activity
Adult beetles are nocturnal and feed on leaves and occasionally fruit, but are not considered economically important. They are active from early May into September, with females depositing eggs under bark and in small cavities in the tree trunk near the ground. Peak egg laying activity takes place in June.

Scouting Notes
Presence of larvae is indicated by sawdust castings pushed from the tunnel, accumulating on the ground beneath the tunnel entrance. Young non-bearing blocks of apple trees are particularly susceptible.  This pest can become a problem in neglected or backyard apple trees.

Check for the presence of sawdust and signs of insect feeding in the heartwood.

Thresholds
There are no established thresholds for round-headed tree borer.

Advanced

Scientific Name
Saperda candida

Identification
Adult round-headed apple tree borers beetles are light olive brown with two conspicuous white stripes running the length of the body. Adult length is just over 2 cm, and antennae are almost as long as the insect. Larvae are pale yellowish white, approximately 2.5 cm long, with a dark brown head and black mandibles.

The round-headed apple tree borer attacks healthy, living trees. Larvae (grubs) feed on the cambial tissue and heartwood near the base of the tree by boring into the branches and the trunk. Presence of larvae is indicated by sawdust castings pushed from the tunnel, accumulating on the ground beneath the tunnel entrance. Girdling of young trees eventually results in a greatly weakened tree, often leading to death. Young non-bearing blocks of apple trees are particularly susceptible.

Often Confused With
N/A

Biology
Hosts include a range of hardwoods including mountain ash, hawthorn, wild flowering crab apple, quince, plum, cherry and apple. Adult beetles are nocturnal and feed on leaves and occasionally fruit, but are not considered economically important. They are active from early May into September, with females depositing eggs under bark and in small cavities in the tree trunk near the ground. Peak egg laying activity takes place in June.

Hatching larvae bore into the tree and begin feeding on cambial tissue. As they grow, they eventually attack the heartwood as well. A single larva can kill a young tree. The life cycle requires two to three years before the larvae pupate and emerge as adults.

Period of Activity
Adult beetles are nocturnal. They are active from early May into September, with females depositing eggs under bark and in small cavities in the tree trunk near the ground. Peak egg laying activity takes place in June

Scouting Notes
Check for the presence of sawdust and signs of insect feeding in the heartwood. This pest can become a problem in neglected or backyard apple trees.

Thresholds
There are no established thresholds for round-headed tree borer.

Management Notes

  • No chemical controls are registered for the round-headed apple tree borer.
  • Many cultural practices used to manage clearwing borers reduce infestations by round-headed apple tree borer.