Sun, Jun 28, 2009 at 1:01 PM
Super huge beetle (at least for the northeast), swollen-looking yellow belly (mama beetle, maybe?), periodically leans forward completely on its head and projects this bizarre pointed appendage from its backside….very weird. I’ve never seen anything like this.
Your female beetle is a Broad Necked Root Borer, Prionus laticollis, and the appendage is her ovipositor which she uses to deposit her eggs. According to BugGuide: “Eggs are inserted into ground (or under litter) in groups. Larvae tunnel downward to feed on living roots of a variety of trees and shrubs. At first they may feed on bark, but then proceed to hollow out small roots. Pupation occurs in spring, about 10 cm under the ground. Life cycle probably three years.”