Sevin will help. Some sort of trap to attract the bees may help. There are no easy answers on this one. Sorry.

That often occurs when fruits are over-ripe or are damaged previously.

You could use a fine netting such as the stuff used for veils.

Most pears are picked before ripe. They ripen from the inside out so if you wait to pick ripe from tree they will be over ripe inside
The yellow jackets are annoying. We let our bees eat the fruit they need some sort of nectar too. I would personally not kill or trap bees they will be helpfull in pollination of your trees next year.
Simple yellow jacket traps work well for those pesky fellas.
What varietie of pear? when is it supposed to ripen? Have they changed any color?
Cut one open if the seeds are dark brown/black they are ready to be picked and ripened in the house.
Good luck I'd be glad to answer any pear questions you have
Happy growing
Cory the son of a fruit freak

I also have problems with various bees. This year I have these huge yellowjacket bees eating my figs, they are getting most of them. What I have found is once the trees get bigger you will get enough of a crop that the bees will only make a small dent in it, so its probably best to just wait it out.

Pears should be picked when they come off the tree easily when you lift a fruit. Then put them in the fridge for a few weeks, and then on the counter for a few days. I'm a bit puzzled if the pears are still small this time of year, that doesn't sound right. My pears are large now. Maybe its a Seckel or other small pear.

Scott