SourwoodGrace · North Carolina, US · Pests & Disease · Aug 10, 2026

Day 3 of Formic Pro and there's a pile of dead bees at the entrance plus brood gaps — normal or did I cook my queen?

Third year, four hives in the North Carolina piedmont. Put Formic Pro (2 strips, full dose) on my worst mite hive Saturday evening. Daytime highs have been 84-86F, so inside the label range but barely. Day 3 and there's a pile of dead bees on the landing board and in the grass — maybe a cup's worth? Also peeked under the lid (didn't pull frames) and I can smell the formic strongly. My neighbor pulled a frame in HER treated hive and saw patchy brood with gaps where there was solid brood before. I knew formic was hard on them but this feels like a lot. Is a cup of dead bees within normal losses? And when is it actually safe to check whether the queen made it — I've read everything from 3 days to 2 weeks. Trying not to spiral here.

#formic-pro#varroa#treatment#queen

▲ 11 votes 💬 4 replies

4 replies

ImkerinLena · Aug 10, 2026

This is within normal formic fallout, especially at 29-30C. Formic kills mites under cappings, which is its great strength, but it also kills some open brood and the workers drag out the dead larvae — that is your brood gaps. A cup of dead adults on a strong colony is unpleasant but not alarming. What would alarm me: bees pouring out and clustering outside, or the colony going silent.

TexasBeeSam · Aug 10, 2026

Been through this in Texas heat. Don't open before the strips are done, you'll just vent the fumes and lose efficacy. Wait until about a week after the treatment window ends, then look for EGGS, not the queen. Eggs mean she was alive 3 days ago and that's all you need to know. Queens do sometimes pause laying during formic, so no eggs on day one of looking isn't a death sentence either — recheck in 4-5 days.

GeorgiaWes · Aug 10, 2026

Agree with the above, and one add: prop the outer cover forward or give them a vent notch if you haven't. At the top of the label range, a little extra ventilation takes the edge off without gutting the treatment. Losing some brood now is the trade for clean winter bees in October. It's worth it.

SourwoodGrace · Aug 11, 2026

Thank you, breathing again. Vented the cover this evening, dead bee pile has not grown much today. Will sit on my hands until next weekend and go looking for eggs, not her majesty. Will report back.

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