GalwayBees · Galway, IE · Pests & Disease · Jul 30, 2026

Bald brood in patches — how do I tell wax moth damage from hygienic uncapping?

Second year in Galway, two hives. Found several patches of bald brood in my stronger hive yesterday — capped pupae with the cappings removed or perforated, white pupae visible and apparently alive, heads up in the cells. Maybe 30-40 cells total across two frames. Google says either wax moth larvae tunnelling under the cappings, or the bees' own hygienic behaviour uncapping suspect pupae. Those are pretty different problems and I can't tell which I'm looking at. Some of the bald cells do seem roughly in a line, but I might be seeing patterns in noise. What's the actual tell? And whichever it is, is 30-40 cells anything to act on, or note-and-monitor? Colony is otherwise strong, good stores, wash was 3 per 300 three weeks ago.

#bald-brood#wax-moth#diagnosis

▲ 8 votes 💬 3 replies ✅ Solved

3 replies

ImkerinLena · Jul 30, 2026 · ✅ Accepted answer

The line IS the tell — you're not imagining it. A wax moth larva tunnels beneath the cappings in a track, so moth bald brood runs in a connected line of uncapped cells, often with a fine silk thread and dark frass crumbs visible with a loupe. Hygienic uncapping is scattered single cells, no trail. Lines + silk = wax moth. In a strong colony it's cosmetic: the bees deal with the larva and exposed pupae usually emerge normally. Note it, squash any larva you find, done. Weak colonies are where moths become a real problem.

CorkBeeRon · Jul 30, 2026

ImkerinLena's covered it. I'd only add: run your hive tool tip gently along the bald line — you'll often flick out the culprit larva at the end of the track, very satisfying. And it's a mild nudge that the colony's comb is older than ideal; moths favour comb with cocoon buildup. Worth cycling those frames out over the next season or two.

GalwayBees · Jul 31, 2026

Found the silk with a magnifying glass — a clear thread along the whole line, so wax moth it is. Evicted one very surprised larva. Both frames are marked for replacement next spring. Thanks both!

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