I remember my grandmother talking about the Kiddie Koop she used back in the 1920s when her two sons were babies. I also saw it when I was young. The wood frame was blue and the fine mesh screen around it was just like window screen. So I gave my main character Maddie a Kiddie Koop (a used one, because she’s poor) for Baby Tommy. The ad above is later, probably from the 1950s, but you get the idea.
Mary Miley's Roaring Twenties 
I remember that they were all for “airing the baby “. Making sure that the baby had fresh air. Outside in the pram or on the porch.
This would have kept bugs and mosquitoes off the baby.
Good point. I hadn’t thought about the bugs. Snakes too. (My grandparents were stationed in the Philippines in the 1920s with 2 little boys, and used to tell us about finding a snake slithering down the rope that held the baby basket.)