Some bees, in their quest for the sugary treat flowers offer up to ensure cross pollination, cheat. Yes, I'm afraid it's so. Some bees will chew holes at the base of a flower to get at the nectar. Several bees I watched yesterday simply took advantage of the space between petals. You may need to click on the picture to make it bigger.
This is fine for the bee, who gets his or her dose of energy, but it doesn't help the flower out much. Not that this species of bee is responsible for pollinating this flower. Not all insects that visit flowers are pollinators. Well, they could be, but just not for that specific plant. Some flowers have evolved a defense against nectar robbing. The catchflies, Silene, have a sticky substance at the base of their flowers to make it harder for anyone to bypass their reproductive parts.
Here is a bee doing things the proper way.
This fellow sure had to perform some interesting acrobatics to reach his reward.
My best guess is that these bees are from the genus, Colletes. Otherwise known as cellophane bees. These small bees were happily sipping nectar from the patch of Snow Drops growing on the upper terrace.