Last summer we had a type of fruit fly, spotted wing drosophilia, infesting our raspberries. The adult fly would lay an egg on the nearly ripe fruit, the egg would hatch, and a maggot would slowly consume the berry from the inside out. But raspberries are softer than green blueberries, so I suspect that this is not your insect pest. You might try to cut open the damaged fruit to see what you can find out.

Oh yeah, the SWD will go after blueberries but I didn't think this early (hard, green). They infested the blueberries late July. Didn't get the raspberries that I could see, but they got the wild blackberries.

I'm wondering if this is cranberry or cherry fruitworm? Supposed to be raining AM, don't think I can go get some berries but I am going to Ag station (bringing soil samples and some TC blackberry canes I think might have cane borers), will try.

Carpenter bees are supposed to sometimes drill through blueberry flowers to get pollen, destroying the potential for fruit. I have a huge population of Car bees that work my blueberries all day long and I still get huge crops which I feel I owe to them.

I saw a blueberry commercial grower guideline once that recommended killing all CBs in the area, but they are my most reliable pollinators. Bumble bees aren't even around when I need them most, in early spring.

Have you found any crumbly, dry frass stuck to the damaged berries, multiple berries with holes that are stuck together, or webbing in the middle of berry clusters along with the above issues? If so, I'd strongly suspect cranberry fruit worm. I've had more trouble than usual with them, especially on my rabbiteyes. You'd probably have to spray a broad spectrum something or other pretty early on to deal with them. Bt might work, but I suspect it would be like trying to get squash vine borers with Bt -- if you they don't ingest enough of it when they bore in from the outside (which is unlikely), they're pretty much safe to continue the damage on the inside. I've just removed and discarded the affected berries in the hopes of slowing their spread next year. A little thinning might not be a bad thing anyway...

Shazaam provided an excellent description of the cranberry fruitworm, which has also been a serious pest for me this year. The only thing I'll add is that the hole in the berry is almost always near the stem end, if it's cranberry fruitworm.

Thanks - I'll go out and look now that it's clearing up (didn't take any to Ag station) but I didn't notice any webbing yesterday.