I know citrus can keep producing well past 20 years old. Has anything changed with it in the last 3 years? More/less fertilizer or water?

No. Just the lack of bees

You could try attracting mason bees to your yard. Their sole purpose is pollination. I have two mason bee houses mounted under an eve of the house. The houses should face SE. Google mason bees for some info. Maybe you can mount a bee house in the tree!!

One way I like to attract bees is to plant borage. It regrows every year from the seeds from last year so it's basically a permanent plant in my yard. They are very easy to control and grow, and they attract tons of bees. If you give them lots of water, they get really big so keep that in mind (I never water mine to keep them fairly small). Another benefit is you can eat borage. It tastes a little like cucumber.

I love borage, it's so pretty. How does it do in a container andy, do you know?

I've actually never tried it in containers. I would imagine it would work pretty well and the sides of the container would probably keep it from getting too big.

I had one that got a lot of water get about 5 feet tall and wide, and the middle stem was about 8 inches in diameter, so they can get pretty huge if you let them. The stems are hollow so they are easy to cut down and decompose fast so they go great in a compost pile.

Those are flax and penstemon, I believe? I've grown both and neither compared even a little to the bee bringing power of Borage :)

Sometimes I go out into my yard and it sounds like a bee hive moved in because of all the buzzing near my borage plants.

Ohhhhh well then I'll be planting some thanx.

I don't see any bees on my penstemon plants, I have 2. Hummers love it but for some reason the bees are not too impressed.

I have an article about attracting bees. Here:

Choose blue, purple
and yellow: Bees find blue, purple and yellow flowers most appealing. Flat or shallow blossoms, such as daisies, zinnias, asters and Queen
Anne's lace, will attract the largest variety of bees. Long-tongued bees will
be attracted to plants in the mint family, such as nepeta, salvia, oregano,
mint and lavender. Long-tongued bumblebees are attracted to flowers with hidden
nectar spurs, such as larkspur, monkshood, monarda, columbine and snapdragons.

- - -

Be careful of mint, it can get out of hand. Keep it in containers to control the invasiveness. Good luck! and keep us posted.

Thanks guys My yard is usually buzzing with activity especially around the red fairy duster we have to take a wide berth because it is literally covered in bees I hope I can attract more with planting the different varieties and putting a mason house in the trees.

What is fertilizing and watering schedule? Citrus are HEAVY feeders.

Are you getting lots of fruit set but a lot of early drop? (some is normal)

Fewer blossoms than previously?

If you have been elsewhere in the yard, they will find the orange tree.

I water once a week slow and deep fertilize with citrus fertilizer and twice a year with my own compost same amount of blossoms but hardly any set and there have been Practically no bees in my yard at all.