Why Cleaning Mason Bee tubes after November is Important

NOTE: I have updated this 2016 post in order to make it appear closer to the other mason bee information

Today I came across two unopened reed tubes which I had forgotten  in the refrigerator so the cocoons had not hatched out.  The image below shows why it is important to clean your tubes out in the winter and not leave them until late spring.

mites3may1
One cocoon remains on the left at the inside base of the tube. It had a live female which when she hatched would have had to crawl out of the tube through several compartments filled with mites, represented by the orange deposits they leave after consuming  parasitised larval bees.  The mites are in the compartments on the right side, toward the open end of the tube.

If people leave mason bee homes out unattended from year to year, the parasite population expands . They wouldn’t be so successful in the wild where mason bee nests are more dispersed in holes in wood or under tree bark. . When we provide homes for them however, along with increasing the bee population, we are also  multiplying  the success of the parasites. So if we are going to encourage bee populations, it is our responsibility to attend to the cocoons in the fall or winter to be sure they are not contaminated with a new generation of mites.