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Ministry of Agriculture, Food and Rural Affairs

red-necked cane boreR

Adult red-necked cane borerRed-necked cane borer damage – broken cane at point of injuryRed-necked cane borer damage – slight swelling and bark splits at point of injuryRed-necked cane borer damage – bark scraped to reveal tunnelingRed-necked cane borer damage – slight swelling and bark splits at point of injury Red-necked cane borer larva
Click to enlarge.

Beginner

Scientific Name: Agrilus ruficollis (Order: Coleoptera; Family: Buprestidae)

Identification:

  • Occasionally seen in raspberries in Ontario.
  • Adults are small, 6 mm long, dark metallic coloured beetles with a flat head and reddish band just behind the head.
  • Eggs are laid on the lower half of the primocanes.
  • Larvae tunnel in a spiral fashion around the cane. Spiralling damage can result in swelling or galls.
  • Infested canes may wilt or dry up above the injury, and often break off at the gall.

Often Confused With

Period of Activity
Adults are active in late June and early July. Larvae tunnel up and down the cane in July and August and overwinter inside the cane. Injury is most frequently observed in late summer, fall or winter when infested canes break off about two to three feet above the ground.

Scouting Notes
Look for the presence of the small beetles on sunny, bright days in June and July. Beetles are most likely to be found on primocane leaves. Examine primocanes and look for swelling and/or spiralling tunnels just beneath the bark. Cut off and scrape the bark around the swelling. Look for a brownish tunnel leading up into the cane and continue scraping tissue along the tunnel until the larva is found.

Thresholds
None established.

 

Advanced

Scientific Name: Agrilus ruficollis (Order: Coleoptera; Family: Buprestidae)

Identification:
This pest, also known as the rose-stem girdler, is seen occasionally in raspberries in Ontario. The adult is a small, 6 mm long, dark metallic beetle with a flat head and reddish coloured band just behind the head. The beetle emerges from fruiting canes in late spring or early summer. Eggs are laid on the lower half of the primocanes. Larvae tunnel in a spiral fashion around the cane. The first few spirals under the bark result in a swelling or gall. The larvae continue to tunnel up or down the cane in the pith. Infested canes may wilt or dry up above the injury, and often break off at the gall.

Often Confused With

Wind damage
Broken canes due to red-necked cane borer exhibit swelling and obvious signs of tunnelling just beneath the bark, while wind damage will not produce any swellings at the site of breakage.

Raspberry cane borer
The two insects are both beetles with orange or reddish colouring in the thorax. Raspberry cane borers have antennae which are as long as their body, approximately 12.5 mm long. Red-necked cane borers have short antennae, and are smaller in size, approximately 6 mm long. The two beetles also damage primocanes in different ways. Raspberry cane borers produce two zipper-like girdles near the tip of the cane, which cause the shoot tip to bend over, while red-necked cane borer larvae cause swellings on the lower portion of the cane.

Biology
The adult is a small beetle, approximately 6 mm long, with short antennae and a distinctive red or orange band on its prothorax. The larva is creamy white, legless, flat-headed and measures up to 20 mm in length once fully mature. Before pupation, the larva shortens and thus the pupa is of a similar shape and size as the adult form; it changes colour from white to metallic black as it matures.

This insect has a one-year life cycle. The adult beetle feeds on young leaves of primocanes between May and early August. The female deposits a single egg in May or June on raspberry primocane bark and once the larva hatches it chews its way into the cane tissue. As it feeds on the primocane tissue, the larva girdles the cane and causes it to swell and form an elongated gall. It also creates spiralling tunnels just beneath the bark, which causes the bark to split. The swelling and girdling of the cane causes it to break, or weaken and die, above the point of injury.
The larva continues to tunnel as much as 13 cm below or 75 cm above the initial entry site, feeding on pith, hardwood and sapwood tissue as it grows. The larva overwinters inside the cane and the following spring, it creates a larger cavity and pupates. After a few days of maturation, the adult emerges in May by chewing a D-shaped hole to exit the cane. Infested canes are very weak and incapable of supporting a full berry crop.

Period of Activity
Adults are active in late June and early July. Larvae tunnel up and down the cane in July and August. Injury is most frequently observed in late summer, fall or winter when infested canes break off about two to three feet above the ground.

Scouting Notes
Look for the presence of the small beetles on sunny, bright days in June and July. The beetles are most likely to be found on primocane leaves. Examine primocanes and look for swelling and/or spiralling tunnels just beneath the bark. Cut off the cane and scrape the bark around the swelling. Look for a brownish tunnel leading up into the cane and continue scraping tissue along the tunnel until the larva is found.

Thresholds
None established.

Management Notes