An insect known as the raspberry cane borer has affected some Wood River Valley raspberries.
Raspberry cane borers are slender, long-horned beetles measuring about a half-inch in length. The insect is mostly black except for a section behind its head (the thorax) that is yellow-orange with two or three black dots and has long antennae. The larvae that live within the cane are cylindrical and legless, white, and get to be about three-quarters of an inch long.
Damage by a raspberry cane borer is easily identified by two rings of punctures about a half-inch apart and located 4-6 inches below the growing raspberry cane tip.
This insect has a two-year life cycle. The adults appear in June and, after puncturing the two rings in the canes, they lay eggs. The eggs hatch in July and the larva begin to burrow toward the base of the cane, where they overwinter within 2 inches below the girdling (area of the cane that has been stripped of its covering). The second season it continues to burrow downward to ground level where it spends the winter and will emerge as an adult the following spring.
The existence of wilting tips characterized by two rings described earlier indicate attacks by raspberry cane borers. For control, prune out the infested canes by cutting a few inches below the girdling or below the larval tunnel by midsummer. Since the life cycle requires two years to complete, regular pruning usually keeps the population in check.
