Chalkbrood is a common fungal disease that affects bee larvae. Chalkbrood pops up most frequently during damp conditions in early spring. It is rather common and usually not that serious. Infected larvae turn a chalky white color, become hard, and may occasionally turn black. You may not even know that your bees have it until you spot the chalky carcasses on the hive’s “front porch.” Worker bees on “undertaker duty” attempt to remove the chalkbrood as quickly as possible, often dropping their heavy loads at the entrance or on the ground in front of the hive. Misdiagnosing this disease is common, because it’s easily confused with chilled brood. You see carcasses at the hive entrance with both anomalies, but with chalkbrood, the bodies are hard and chalky (not soft and translucent as is true with chilled brood). No medical treatment is necessary for chalkbrood. Your colony should recover okay on its own. But you can help them out by removing mummified carcasses from the hive’s entrance and from the ground around the hive. Also, usually one frame will have most of the chalkbrood cells. Remove this frame from the hive and replace it with a new frame and foundation. This action minimizes the bees’ job of cleaning up. Also consider replacing your queen by ordering a new one from your bee supplier (or by providing one of your own if you are raising queens ). Your help quickly arrests the spread of the fungus.
From : “Beekeeping For Dummies” By Howland Blackiston.