Buzz off

Searching for a blip, resorted to stalking bees around the garden. Yesterday's trip produced a bonus, this lavender is one of the few things attracting some of the small number of bees. One thing has me puzzled, the greatest number were heading for the laurel bushes, which have no flowers, then they seemed to go for the undersides of the leaves. I presume they were looking for aphids, - to steal honeydew?