Red-necked or Blackberry Cane Borer
Head: Small, dark bronze. Top of head deeply indented, appears as two lobes, indented area continues down face to mouth.
Antenna: Short, blackish-bronze. Segments steak-knife-like (serrated) on 4 to tip.
Thorax (Pronotum): Main ID: Metallic reddish-coppery. Base margin smooth, even, wrapping around sides of head. Side margins slant upward to wings. Lower margin deeply wavy, outside corners pointed.
Wings (Elytra): Slightly shiny, black. Base margin follows contours of lower margin of thorax. Shelf at side edges, shiny, sometimes appearing whitish. Wing tips bluntly rounded.
Legs: Black, short. Thighs (femora) slightly thicker than shins (tibiae). Claws curved under foot.
Abdomen: Black. Males with some hair at sides.
Size: Adults 6 to 7 mm long. Larva to 17 mm long.
Flight Time: June to August
Habitat: Forest edges, meadows and fields with blackberry or raspberry.
Food: Adults feed on leaves of Blackberry (preferred), Raspberry and sometimes Purple-flowering Raspberry Rubus, leaving holes in the middle of the leaf and lots of frass. Adults play dead.
Life Cycle: Females lay eggs in June and July on new growth stems, usually near the base of the plant. Eggs are covered with a yellow liquid, liquid then turns white. Hatching in about 3 weeks, the larvae stay within the protection of the yellow/white liquid and bore directly into the stem. They feed on the stem in a spiral fashion which produces a 3 to 8 mm long gall – Raspberry Gouty Gall, causing the bark to split. Larvae are long 17 mm., white to cream with a flattened, enlarged head. Overwinter and pupate in the spring (April to May) in a larger chamber at the middle of the stem. One generation per year.
Parasites: Beewolf Wasp Cerceris fumipennis. Some Braconid Wasps have also been reported.
Comments: Essex County –Point Pelee and Ojibway Prairies; Kingsville, Harrow. Widespread in northern Ontario, south to Guelph and Toronto.
For information on synonyms, references and type specimens see next page