Bluebirds and House Wrens

Today the House Wren went into the bluebird nest box while the Bluebird parents were out foraging and speared each egg one at a time and dropped it out of the entrance hole. We lost all three. Took the box down. We have seen the wren on the other house as well, but the sparrows who inhabited it were good at chasing it off. The sparrow eggs were duds - laid on the 17th and the following few days, three weeks and counting no sign of life and the parents had given up visiting the nest box. They did make the eggs cozy with of all things -shredded cigarette filters! The eggs should have hatched 11 days after they were laid. They looked perfect-no holes. I discarded the nest Friday. The bluebirds have been checking the now empty box out so we put a "wren guard" over the entrance. Basically it's an awning that blocks the hole from view. Should probably have done that to the other box, but have not seen the wren near the box in weeks and thought they were safe. Don't know if the bluebirds will move in to the other box, it may be too late in the nesting season.
Unfortunately, house wrens have a territory larger than our property. They have been terrorizing the boxes next door as well. They need something like 230 feet of space. The bluebirds may be able to use the boxes in April and then we will have to plug them up, take them down, or leave the doors open to discourage the wrens. I am almost sorry we got the boxes to begin with.