For visualizing mandibular mycangia, beetle heads or bodies should be fixed in 96% ethanol, immersed in 30% hydrogen peroxide for 24 h, and embedded in paraffin.
Preparates can be sectioned on a microtome at 5 μm and stained with hematoxylin (to emphasize nuclei in fungi) and eosin (to visualize proteins, muscles, and other beetle tissue).
- The immersion in hydrogen peroxide is critical for softening beetle exoskeleton and to avoid fracturing.
- The angle of beetle immersion in the wax is also critical. It depends on what mycangia you are interested in, what angle you want to slice them, and what is the angle of attachment of the wax sample to your microtome. You may need to play with the beetle position as the wax is hardening.