Hi Lindsay ... I saw one or two like this this spring as well. I think there was also a higher 'slug index' in the hives when I first inspected. I have colonies in Fife and Ardnamurchan. All survived the winter, though I lost 10% due to failed queens. These boxes were well-populated but one queen was a drone layer and the other was just not laying at all.

Fife has been bl%%dy cold. I just checked ... 17 nights of frost in April (the 10 year average is ~3-4) and an average temperature of 5.9°C compared to the average of about 9.5°C (data thanks to the excellent Muchty weather website which is based on a personal weather station down the road from one of my apiaries). The good colonies are doing well despite this, with some being almost full of brood, first supers on and filling with fresh nectar (almost certainly OSR). The strongest were starting to make queen cells and I've (ambitiously) started queen rearing and will be back there this w/e for grafting. However, most weren't this well advanced and I'd predict aren't going to be strong enough to properly exploit the main OSR flow which will be starting in the next week or so.

Ardnamurchan has also been cool with bees only flying well in the middle of the day. Pollen (gorse) has been going in well for a month but they've needed the stores boosted and will probably need syrup today when I check them again. The winter was long and wet (no surprises there) and I didn't see a bee until the end of February. Queen rearing here won't be starting any time soon.

I've just realised this should really have gone in the 'daily' thread ... so back to the mould for a closing thought. I only see it on the outermost frame and usually in cedar boxes where the bees tend to avoid these frames due to the cold. In poly I regularly see the cluster up against the sidewall, even in midwinter.

Cheers
David