Most of us are garden bloggers anyway, can you guess what this structure is?
It is the pistil, most specifically the stigma of a squash flower. There is a well full of nectar that makes this colony of ants very happy. A squash flower is only alive for one day, so those ants are taking advantage of the short amount of nectar supply. The nectar is glistening with the sunlight, some even look like swimming in it.
This flower is not fertilized i suppose, as there is no available male flower nearby. Once-in-a while i also take glances and i haven't seen any bee alighting on it. I can be sure, it is not pollinated.