Wow sounds so nice!! The bees are going crazy for the wild arugula flowers in my garden right now. Wish it was lilacs.
For some reason I'm thinking lilacs don't grow well down here in Texas... my yummy gardenias are blooming but no bee visitors. When they were budding the ants kept trying to farm aphids. We had an ongoing battle; I would wash the aphids off and hours later the ants would be back at it!! They are very persistent little creatures but I was too and I won that battle.
Bees do seem to like flowers from plants in the Brassica family.