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Adult blueberry stem borers
are slender, elongate beetles with light brown or yellowish bodies. Facts:
- Blueberry stem borers have two dark spots on the dorsal surface of the thorax and a dark lateral margin on each wing cover.
- Beetles are about 5/8 inch in length and have slender antennae that are nearly as long as the body.
- Each larva lives only within the stem or crown of its host plant.
- Larvae have legless, cream-colored bodies with dark brown heads and mouthparts.
- A distinctive patch of tiny, dark-colored spines is present on the upper surface of each larva's body just behind the head.
- Larvae reach a length of about 1.25 inches when fully grown.
- Adult females lay eggs individually under a flap of bark cut near the terminal end of a blueberry cane in early summer.
- Larvae hatch in about two weeks.
Damage: At first, the larvae tunnel upward within the cane (often killing the terminal), then reverse direction and burrow toward the crown of the plant.
2 inches to 10 inches of the stem may be excavated during the first year.
Larvae become inactive with the approach of winter but resume feeding in the spring.
After reaching the crown of the plant, they move to adjacent stems, continue feeding for the rest of the year and complete development during the spring of the third year.
- Infested plants can be spotted by looking on the ground for characteristic mounds of frass (droppings or excrement of insects).
- Stem borer injury can be minimized by removing infested canes or wilted terminals as soon as larvae are detected.
- Cut stems well below their hollow section to ensure larvae will never reach the crown of the plant.
Stem Borer. IPM North Carolina State University. 05 June 1997. Retrieved 14 July 2010.