A bunch of causes are known, I believe the main one is a mite, but there are many contributing factors: https://www.epa.gov/pollinator-protection/colony-collap

A bunch of causes are known, I believe the main one is a mite, but there are many contributing factors: https://www.epa.gov/pollinator-protection/colony-collapse-disorder https://www.epa.gov/pollinator-protection/colony-collapse-di...