This is the damage, plus the perp at the scene of the crime...no idea of the original culprit though someone told me that it is the 'stinky bug', which I've always known as the green shield bug. But although there are a few around now I didn't notice that many earlier.
The maggots were tiny when I first noticed them, am certain they didn't originate at blossom time, and someone else told me it always happens when it rains at the wrong time (ie when the fruit is ripening)
Hope the pic quality is good enough to see and identify(had to reduce the size drastically in order to upload it)...and that someone has an answer.
My later apricots and nectarines are due to start cropping soon and I'm tempted to pick them before they are ripe, so at least there might be some usable, if somewhat sharp, fruit. This is what the locals did recently, and I wondered why they had picked them when they were still greenish...now I wish I'd done the same.