Well, once again MJ has beat me to it and already reared the forked fungus beetle from an artist's conk
...but I'm still going to post this because I spent a lot of time putting together this series (not knowing she had already documented similar aspects of this species' life history here in IA) and because the adults shown were reared from young larvae collected in small mushrooms during the dormant season. Specifically, MJ and I were taking a wintertime stroll through her property in February when we came across artist's conks with an insect sign I had seen repeatedly but never deciphered: small, dark brown, cocoon-like domes lined up along a contour on the upper surface of the mushroom.
These turned out to be capped entrances to tunnels leading into the mushroom. Inside the tunnels were small beetle larvae.
I brought a few pieces of mushroom home to rear, put them in a jar, and pretty much forgot about them, until I checked up on them during the summer and WHOA, TONS of frassification had happened. Before long I had my first adult, and then, a short while later, several more. By early September 2017, the few small mushroom pieces collected in February (and shown in this first photo of this series) had produced five adults and a pupa! The sheer amount of frassification was astounding (note the pile of frass and shavings, and the gaping hollows in the mushrooms). The fungi shown were all solid and fully intact when collected in February, save for the short, narrow tunnels of a few young larvae.
Thank you to MJ for the use of her microscope to produce the images of larva and tunnel-cap.