Hi Melissa--Sounds like your Masons, most of them hopefully, will do OK. You say the nights have been below 55. That's OK. That likely means that your days have been pretty warm. They need it over 50 during the day to emerge and by this time in April they want to get out into the wide blue yonder anyway. Many should return to the empty tubes to lay eggs and others will find somewhere else. Ten acres is a lot of apple trees. They generally roam about 200 yards, I think, and will retrun to original nest. Any further than that and they will look for other nest sites. Good luck and hapy gardening!!
Tom from Boise

It sounds like you have everything set up very well to be successful with mason bees. You should have a nice long bloom period with all those different kinds of fruit trees. One note on pears - the nectar tends to be rather thick and the bees find it less desireable than the other fruits. You can get better pollinaton on the pears if you keep them well watered during the bloom period. This will thin the nectar a little.

After two weeks from the first emergence you can take the straws out of the cardboard tubes and open them up to see if there are still some mason bees in there. The easiest way I've found is to unroll the paper straws along the spriral joint. The brown leathery cocoons can be placed behind the chicken wire to let the bees chew their way out. You could open the cocoons and let them out right away, but it's not easy to cut the leathery material without harming the bees inside. When you open the straws, check the unfilled chambers carefully. If you see something that looks like a fine pinkish sawdust it could be mites. If you find anything like this, seal it in a plastic bag and throw it in the garbage (or burn it). Actually, it would be a good idea to take everything except the cocoons and put it in plastic bags in the garbage.

One final thought - 10 acres is a lot of fruit trees. Consider putting up 1 or 2 more nests spread out throughout the trees to keep the flight distances shorter. One hundred yards is the general rule of thumb for the maximum distance from nest to flowers.