1.  I have purchased a cute little wooden bee house and I need a bee for it.  Can you sell me a bee?  Answer:  Yes and about 249 extras.  I don't stock Osmia lignaria, they are native to the US.  I do stock Osmia cornifrons because they are the best at Orchard Pollination, however they are not native to the U.S..  To get O. cornifrons  established in an area you need at least 250 bees and enough nesting holes for them to nest in.  The little blocks just don't have enough holes .
2.  Don't you make these wooden bee homes?  Answer:  No, I have no association with the sellers of the little bee homes.  However they are a cute novelty.  I sell the bees and  nesting units that are used for pollinating orchards.  You would have to put out 27 of  of those little blocks of wood for every 3/4 to 1 acre of trees.  That would be very expensive, time consuming and take up a lot of space.  On the ones I have seen, the holes are drilled across the grain and I feel that they are too rough inside to attract the bees.
3.  All that I've seen nest in my wooden bee houses are wasps - what could be the problem?  Answer:  Osmia strongly prefer a smooth hole to nest in - if your block of wood is drilled into the side of the wood instead of the end than the hole will most likely be very rough and not acceptable to Osmia.  Forcing the bit in or using the wrong type of bit can also make the holes rough and unacceptable to the bees.
4.  How do you ship the bees - do you have to put them in special containers?  Answer:  I do not ship the bees when they are active so no special containers are needed.  I normally start shipping bees in the fall and continue until spring  (depending on the weather).  Usually shipping stops near the end of March - sometimes it goes as late as mid April - if it gets real late we can ship overnight COD for an additional charge if the bees haven't been set out yet (a few males may emerge but that is no loss.
5.  Where should I keep the bees when they are not in the orchard.?  In the shed or a unheated garage with the lids off.  I don't let them stay in the orchard after their active season because I don't want a bunch of the holes filled with wasps nests.  I also like to trap any parasitic wasps that may have gotten through the tube coatings with a small light and a pan of oil.  Some wasps will have nested before I remove them from the orchard - those wasps emerge during the summer (they have a couple life cycles each year) and that leaves the holes open for bees to nest in the following spring.
6.  Why do you X-ray the tubes?  The bees often make false nests that have plugs in them - I don't want to send you empty tubes.
7. Why do you wait until fall to start shipping bees?  When I X-Ray the tubes - I don't want to mistake wasp nests for bee nests - the wasps will emerge once they are adults - by waiting, all of the wasps will have emerged from the tubes and you will be sure to get Osmia instead of wasps.  Other suppliers just count the plugged tubes and send them, wasps and all.
8.  How do you refrigerate them in the spring?  I use an air-conditioner on the shed and have a standard temperature thermostat on the air conditioner and I leave the blower on constant.  I keep them no higher than 45 degrees.  Orchardists with coolers can use the now empty coolers to keep them cool and above 70% relative humidity.  If you don't have a refrigerated shed you can put the lids on the Ezbee Nesters and place a damp paper towel inside the containers before putting them inside a refrigerator.  Then once a week re-moisten the paper towel and let a little fresh air in.
9.  When do you start to refrigerate them for apple pollination?  When I see the buds start to swell on the forsythia bushes and other plants ( the bees normally emerge about the time the forsythia blooms.)  Or when the grass starts to turn green. - whatever comes first.
10.  How do you know when to put the bees out for apples if you refrigerate them?  You need to try to time it for 5-7 days prior to bloom.  I wait until I see pink on the apple blooms or when they start to break  tight cluster at the latest. Why? So there is plenty of other bloom in the area, because the female bees need to have time to emerge and to eat some pollen so that their ovaries will finish developing.  Emerging takes 2-3 days and then their ovaries take another 24 hours to finish developing.  I want there to be plenty of other bloom available in the area when they emerge so that they won't leave the area searching for food and then nest somewhere else.
12.  If there is a lot of other bloom in the area then won't the bees will be too busy working those bloom to work my trees like honeybees do? No, Osmia prefer fruit trees (apple, peach, pear, plum, etc.) over any other type of bloom and will stop working everything else when the trees start to bloom.
13.  What if the weather turns cold again,  will the bees be alright?  It always seems to.  If the bees haven't emerged or as long as the bees that have emerged are able to get nectar shortly after they emerge, then they are able to survive staying in the cold again.
14.  Why should I change the nesting holes every 3-4 years? Old nests can contain a lot of false nests - unused holes that are sealed.  The bees will not dig out old plugs and so those holes are unusable.  Any time an egg that is in the back of the hole  fails to develop or gets knocked off the pollen ball or an adult fails to emerge and it is in the back of the hole, there is less available area in the tube to nest in.  Because the bees do not clean out the holes past the last intact plug, so over a few years the nesting holes become clogged with failed cells, these pollen balls and dead bees can cause molds and fungus to develop that can kill young larvae in the remaining portions of the tube if the tubes get wet or dampened by high humidity.   
15.  Do these bees get the mites that are killing the honeybees?  No.  The adults  have never been found to have any type of honeybee mites and because of the annual cycle of their development the honeybee mites can not infect the young bees.  Tracheal mites spread  from adult to adult, the adults of these Osmia are active only about 6 weeks in the spring before they die and they never meet their adult young because they will not emerge until the following spring - so the young  don't get infested with them.
16.  Do they sting? The males have no stingers and the females use theirs only for self defense.  They do not defend their nests.  You could go right up to the nests and hit them and they will only hide (don't it could dislodge some eggs from their pollen balls).  But if you were to grab one or pinch them the females would sting.  However, their sting is about like getting poked with a needle - or maybe a small sliver.  It hardly hurts at all.