Raspberry Cane Borer
W.J. Rayment / -- The Raspberry Cane Borer, known by its Latin name as Oberea bimaculata Olivier. It is the larval stage of a black beetle. When the female beetle is ready to lay its eggs, it finds a likely raspberry or blackberry cane and girdles the top in two concentric rings about one-inch or a little over two centimeter apart. The Insect lays its eggs in the cane between these two girdles. Another telltale sign is that the girdling strangles the top part of the plant and it quickly withers. This cuts off excess moisture to the top of the plants that could be harmful to the borer's egg.
When the larva hatches, it bores its way down the stem and wreaks havoc on the entire plant. It can reside in the cane for more than a season. For homeowners, the best way to deal with the depredations of the borer is to remove the girdled portion before the larvae has the opportunity to bore. Be sure to destroy the removed canes completely to control the infestation. For commercial growers, destroy wild canes within 500 feet or 150 meters of cane fields.