Anyone out there know which species of chalkbrood attacks Osmia? or is the material just mould on the pollen. If not, here is a contact for someone who might know, or might be interested in getting some samples to find out. He has worked extensively on the moulds, yeasts and bacteria of leafcutter bee nesting material. Also on the use of paraformaldehyde as a nest fumigant. sorry I don't have a high tech address for him. D. W. Goerzen Saskatchewan Alfalfa Seed Producers Association 107 Science Crescent Saskatoon, SK CANADA S7N 0X2 good luck Kerry Clark, Apiculture Specialist B.C. Ministry of Agriculture 1201 103 Ave Dawson Creek B.C. V1G 4J2 CANADA Tel (604) 784-2225 fax (604) 784-2299 INTERNET [log in to unmask]