I once went to Mackinac Island in Michigan and all of the victorian and colonial houses had blue eaves. I remember it was for a reason I think it was something to do with birds...

I don't know about the birds but it could be a area thing. In Gulfport Florida it's like walking back in to the 40's and 50's. Red brick streets, no new construction, all the houses painted in vivid hues, lime green, cobalt blue, chartreuse =, etc. The downtown section is a collection of art and crafts shops. Perhaps that's what you have up there in Mackinac Island.
Regards, b Tom

It is supposed to deter birds from building their nests in the eaves of the house by tricking them into thinking the eave is part of the sky.

I don't know if it works or not. Guess I will paint my eaves blue and see what happens.

Some people believe it keeps insects, bees and wasps in particular, from building nests in the eaves since, as the previous poster stated, it looks like the sky. I guess they're not color blind!

Being a painter that lives in a very old town, many of our homes porches have the light blue paint on the ceilings.

Not too long ago nobody had air conditioning. Most door entrances consisted of a wood door and a screen door, no storm doors back then.

The old screen doors were very basic. Hinges and the big heavy slam spring acting like a door closer.

Because of that configuration and no air conditioning many homes had porches so when it rains one could leave the wood door open and let the cooler rain air blow in.

This worked great expect for one draw back. Flys loved to hang on the porches inside ceiling and use that as a staging point to fly into the house when the screen door was opened.

Someone figured out that if you paint the porch ceiling with blue paint that helped reduce the amount of flys that hung out which in turn cut done the chances of a fly getting onto the house.

Yes it actually does work. Best guess with our logic is that some flys may think the ceiling is water and won't land on it. Not sure what a fly actually thinks.. This was taken to the next step with eves thinking when opening a window by the blue eves that also would cut down the odds of letting a fly in.

Note: the blue paint only seems to effect flys and nothing else of insect or birds.