When I saw this photo that I took in a room upstairs in our house three years ago I suddenly realized that we don't have ladybugs wintering there any longer. For the first nine years we lived here I'd become adjusted to the fact that they got into that room from an undetermined entryway. There were never so many as to be a bother. They rarely flew, keeping mainly on the window sills and walls around the windows. I considered them little blessings and it cheered me to look at them on dark winter days.
Then we had all the windows in the house replaced last summer, a huge improvement to this old house built in 1910. Many of the windows downstairs were painted shut so, after the installation of new windows, last summer was the first time we could enjoy fresh air in those rooms. The rickety windows upstairs, however, weren't painted shut. This meant that even prior to installing new windows we had a cross draft upstairs in summer, but we also had air conditioning all winter long.
Now it is obvious. The ladybugs used gaps in the upstairs windows to escape the cold of winter. As we enjoy a lack of drafts and a reduced heating bill we have sealed ladybugs out from the shelter they sought by instinct for who-knows-how-many-years, even decades before we bought the house. What a sad and sterile consequence of our home improvement/energy reduction efforts.
I wonder if there are ladybug houses to buy or build. I'm seriously going to find out. We do not use pesticides in our yard and have welcomed ladybugs for the purpose of pest control. If there's some kind of shelter available for them it would be great to continue to provide a year-round environment for them. I hope it's not too late.