mn_newbee · Minnesota, US · Beginners · Aug 10, 2026

Mold floating in my top feeder syrup after 5 days — how much should I be mixing at once?

First year, two hives in Minnesota. I mixed up a big batch of 1:1 last weekend (about 2 gallons) and filled both top feeders. Went to top them up today and there's grey-white fuzzy stuff floating on the surface of one, and the syrup smells a bit sour. It's been high 80s F here all week. Did I just poison my bees? They were still taking it yesterday. And practically — how much syrup do people actually mix at once in summer? Do I need to be dumping and scrubbing these feeders every few days? I've read about putting vinegar or a splash of bleach in the wash water but I don't want to make things worse. Feeling a bit gross about the whole thing honestly.

#feeding#syrup#mold#top-feeder

▲ 7 votes 💬 4 replies ✅ Solved

4 replies

CorkBeeRon · Aug 10, 2026 · ✅ Accepted answer

You haven't poisoned anyone — bees are pretty good at refusing syrup once it's properly off. But dump that batch, it's fermenting. In warm weather 1:1 goes over in 3-5 days easily. Mix only what they'll take in 2-3 days, and keep the spare in the fridge where it'll hold for a couple of weeks.

GeorgiaWes · Aug 10, 2026

22 years in Georgia heat here, so I know moldy syrup well. Smaller batches is the real answer, but for cleaning: hot water and a stiff brush, then a rinse with a weak bleach solution (a capful in a bucket), then rinse THAT off thoroughly and air dry. Vinegar works too if bleach makes you nervous. The feeder needs to smell like nothing when you're done.

VTBeeHannah · Aug 10, 2026

I had exactly this in July my first year. One thing that helped: I stopped filling the feeder to the top. Half-full, refilled twice a week, and mold basically stopped being a problem because the syrup never sat long enough.

mn_newbee · Aug 11, 2026

Thanks all — dumped both feeders, scrubbed with hot water and a splash of vinegar, and mixed a much smaller batch. Rest is in the fridge. Feeling less gross already.

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