Paraffin sectioning was completed according to the procedure in Li et al. (2015) (link). Heads were aseptically removed from the pronotum before sectioning. Once removed, beetle heads were fixed in 10% neutral buffered formalin (StatLab Medical Products) for 24 h and then soaked in phenol for 6 d at room temperature. Heads were treated with an automated tissue processor (Shandon Excelsior- Serial # EX01110212) to allow desiccation of tissues and infiltration of paraffin and subsequently embedded in paraffin blocks. We used a Microm HM 325 rotary microtome (Walldorf, Germany) to cut 10-μm transverse sections. Selected slides containing mycangia were confirmed by immediate observation, and were dried at 58°C in a lab oven (Boekel 107800) for 3 d, then stained with Harris-hematoxylin (Richard Allan Scientific # 7211) and eosin-phloxine (Surgipath # 080117), and examined and photographed using a Nikon Eclipse E600 compound microscope (Nikon Instruments, Melville, NY) with a Nikon Digital Sight DS-Ri1 high-resolution microscope camera to acquire brightfield images.