Who wrote the Itsy Bitsy Spider, and how old is it?
Nobody knows who wrote it. The earliest known printed version is from 1910, so the rhyme is well over a hundred years old and may be older still.
The first version in print
It appears as the “Spider Song” in Arthur Walbridge North’s 1910 book Camp and Camino in Lower California. That early version doesn’t match what we sing today. According to Mental Floss, the spider climbs its own web, and early versions used words like “bloody” and “blooming”, which didn’t last in the nursery.
How it became today’s song
The words most families know were published in 1948 in Ruth Crawford Seeger’s American Folk Songs for Children. Like most folk songs it was passed from person to person, changing along the way, which is why no single author can be named.