Why should you harvest cocoons?

In the wild, nesting holes are spread across the landscape and natural nesting sites change every year. In our man-made bee homes that are designed for our convenience, the nesting holes are next to each other and diseases can be easily spread. Pests and scavenging insects are attracted to the smell of lots of bees nesting in one spot.

Opening nesting material to harvest cocoons is the best way to eliminate pests and disease. The most common problems that are solved by harvesting cocoons are:

  • Pollen mites: they eat the pollen loaf before the bee larvae can. If left in a nesting hole, the mites hitchhike back to your yard and accellerate the problem. The same hole now has pollen mites spread throughout the hole, which when new pollen is brought back, more mason bee egg chambers are dead. This cycle quickly show

  • Chalkbrood: a deadly fungal infection that is picked up on flowers that has been left by other mason bees. If left inside a nesting hole, bees deeper in the hole must move past the chalkbrood and now spread the spore to the yard and on the mason bee house. A new female using this old hole equally spreads the spore as she moves in and out. 

  • Parasitic wasps: gnat-sized wasps that lay their eggs inside of developing bee larvae, killing the bees from the inside out. In the following season, the wasps emerge later in the season and then parasitize new mason bees.

You can learn how to harvest bee cocoons in our Learn section.