At rosybee we plant about half an acre of borage each year, just because its so good for the bees. Its particularly loved by the honeybees - so I am hoping its boosting our honey - but we see plenty of bumblebees on it too.
For this season, I sowed a large section last September and it over-wintered well and started flowering in April. Now it is nearly over but the spring sowing should start to flower in a few weeks.
The honeybees go for the nectar and the bumblebees appear to collect both nectar and pollen, the latter being very pale, almost white.
Each week I try and pick as sunny day and count how many bees/ square meter. The average has been about 6 bees with a ration of 5 honeybees to one bumblebee (mainly bombus pratorum, hypnorum and a few laidarius and terrestris.) Because of its sheer attractiveness and the number of weeks of flower, those two factors combine to make it one of the best bee-plants we have found. We will combine these stats with the results for all the other plants we grow and aim to publish a ranking towards the end of this year.