Celyphid Beetle Fly

Three days after my spotting of some Celyphus spp. in our front yard - https://www.projectnoah.org/spottings/407467512, I went back to the same plant to see how they were doing. This was partly because we had really bad weather during those three days, but also because I wanted to check on the two flies that I thought might be juveniles, to see if any development had taken place which might clarify the situation. I could only see the one remaining specimen shown in my photo above. The others were gone. I checked back several times in the next week or so, but never saw any Celyphids on that plant again.