Frank M. contacted me recently about his findings at his yearly mason bee workshop. A most interesting series of photos- with permission.
“This photo shows some extraordinary wiry frass, even more wiry than the material that I showed you last year from the 2010 harvest. Any ideas? There is also some fluffy stuff in the same chamber and the one next to it, similar to the material in one of the images on one of your blogs.”
This beautifully constructed chamber inside a routered piece of wood, has concave mud walls. It normally contains one masn bee cocoon, but something has entered it. The chamber contains frass- or insect fecal material. According to Bosch and Kemp (2009) wiry frass is likely produced by one of two insects found in masn bee nesting tunnels. One is the cuckoo bee. If there is a cocoon amongst the mass of frass- then it would be the cuckoo bee. If there is no cocoon- it is most likely the spider beetle. It is about 2-3mm long with 4 white patches on its back and long attennae. Both insects eat and destroy the mason bee larvae and its food. They both invade the chamber when it is pretty close to being sealed by the bee.