Bronze birch borer larvae and pupae were detected in small branches through the use of a portable X-ray unit. The optimum exposure time was 40 sec at 55 kV.
Ball, John and Simmons, Gary
"Detection of Bronze Birch Borer Larvae and Pupae by Radiographs (Coleoptera: Buprestidae),"
The Great Lakes Entomologist, vol 17
Available at: https://scholar.valpo.edu/tgle/vol17/iss4/7