Black spots on mason bee cocoons

Mason Bee Larva Frass

During mason bee cocoon harvest, many people ask about the little brown or black flecks that are found throughout their nesting materials.

Don’t worry, these are not a sign of disease or pests. As the mason bee larvae eat the pollen loaves they produce waste, this is also known as mason bee frass. When the larvae spin their cocoons they push the frass outside of the cocoon. It may break into small pieces, or remain unbroken in long loops!  The frass can take a little friction to remove any stuck to the cocoon during washing.

• Related Articles

• Moldy mason bee cocoons

  In most cases, a little bit of mold on the outside of mason bee cocoons is harmless. However, you should remove any excessive mold before it does damage your hibernating bees. About mold: mold is a spore that starts from a food source and typically ...

• Feeding Early Emerged Mason Bees

  How do I feed mason bees that emerged before my flowers are open? Feeding Early Emerged Mason Bees  Don't worry, you can provide early emerged mason bees inside of your HumidiBee with a couple of options. Mason bees have their own personalities and ...

• Troubleshooting why mason bees did not nest in your bee house

  Why are mason bees not nesting in my bee house? For first-time mason bee raisers, this is our most common question in the spring.  First, please be patient. It takes time for the mason bees to emerge from their cocoons and it can take up to two weeks ...

• What to do when mason bees do not emerge

  Mason bees emerge when the time and conditions are right for them - usually in the spring when temperatures are nearing 55F. Depending on your weather patterns it can take two weeks or longer for mason bees to emerge from their cocoons. ...

• Troubleshooting why leafcutter bees did not nest in your bee house

  Why are leafcutter bees not nesting in my bee house? For first-time leafcutter bee raisers, this is our most common question in the summer.  First, please be patient. It takes time for the leafcutter bees to emerge from their cocoons and it can take ...