GalwayBees · Galway, IE · Pests & Disease · Jun 16, 2026

Chalkbrood mummies in the swarm I hived two weeks ago — is the colony doomed?

Hived a decent prime swarm two weeks back, my second season and first swarm, west of Ireland so it's been damp and cool as usual. Yesterday I found maybe a dozen white chalky mummies on the floor and a couple on the landing board, and some patchy capped brood with a few cells opened up. I know chalkbrood is fungal but everything I read gives conflicting advice — some say requeen immediately, some say ignore it. Is it normal for a fresh swarm to get it? They're only on five drawn combs so there aren't heaps of bees covering the brood, and we've had three straight days of rain. Do I treat, requeen, or just wait?

#chalkbrood#swarm#brood-disease

▲ 9 votes 💬 3 replies ✅ Solved

3 replies

AbejasCarla · Jun 16, 2026 · ✅ Accepted answer

Wait — this is textbook and it almost always clears on its own. Chalkbrood (Ascosphaera apis) loves exactly your situation: a small new cluster stretched thin over fresh brood, cool damp weather, brood at the edges getting chilled. There's no approved treatment anyway. As the swarm's population builds and they can keep the whole nest at 34-35°C, it disappears. Help them: reduce the entrance, make sure the floor drains, don't give more space than they can cover. Only think about requeening if it's still bad in a strong colony a month or two from now — then it's genetics.

DrentseBij · Jun 16, 2026

Second all of that. One thing worth doing: scrape the mummies off the floor and rake up any on the ground in front — they're loaded with spores. The bees pulling mummies out is actually a good sign, it means hygienic behaviour is working. I see a touch of chalk in most of my Drenthe swarms in wet springs and I can't remember one that didn't outgrow it.

GalwayBees · Jun 17, 2026

That's a weight off, thanks. Entrance reduced and floor scraped clean this evening. They're bringing in loads of clover pollen between showers so hopefully the population catches up soon.

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