I never spray my garden for bugs. The birds eat all the bugs. I like wrens they eat 2 times their body weight in bugs every day. Wrens are nice they love to sing none stop all day long and they will land only 8 feet away and sing their lungs out.
After 6 years this is what is left of 25 bird houses. Wood cracks and falls apart it is easier to build new houses than to put 15 broken pieces of wood back together.
Plane un treated un painted wood works best but pine does not last long in the weather. Birds will not stay in pressure treated wood houses until it stays outside in rain and weather for about 3 years. I think birds don't like the smell they don't like newly painted bird houses either.
Wrens like houses that are 8 feet or higher from the ground but no higher than about 14 feet. Door must be facing East I don't think they like the hot even sun shining in the door.
Bird houses must be vented too. Vent holes in the floor and vents at the point of the roof. Houses need to be in the shade birds don't like hot houses in the sun.
The wide door serves several purposes. It makes it easy for the mother and father bird to get sticks and twigs through the door to build a nest. The baby birds like the wide door they can all stick their head outside no fighting over who gets food. Mother and father bird do not have to go inside each time to feed the babies.
Birds build a new nest every year soon the house is full to the top, the roof comes off by removing 2 screws on each side and the house gets cleaned out. I put the houses up about 10 feet high with the door facing east and when weather gets right the birds move in. Wrens are interesting birds they will build a nest in 3 houses but only lay eggs in 1 house. Click the picture it gets larger.