Parasites of Mason Bee Colonies.

  • Occasionally I will take a sample of several dozen cocoons that are in cold storage and test them for viability. The longer they remain in storage before release, the more likely that some parasites will get a better head start.
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Once the temperatures are up on sunny days, cocoons placed out near their prospective homes will start cutting their way out of the cocoons and fly off to get materials to fill their own tubes for the coming year.  If there are remaining cocoons unopened after a week and a half of warm weather, then it may be worthwhile to check them for parasites. You can open a cocoon with a sharp box-cutter blade, carefully picking away at the tough cocoon. If the bees are healthy they will leave within a few minutes. You may encounter the following parasites and if so you should get rid of them.  I have included some here that I not quite sure about  as well.  These parasites are natural, but when, as with many monocultures  we concentrate many of one species together, the chance of pests finding a good place to thrive is increased.

frasse
The small black cigars are frasse, (insect manure.)