As I was recently driving north on Highway 65 in northern Missouri, I saw numerous hedge ball trees full of the strange yellow fruit. My grandmother used to put hedge balls in her basement to get rid of crickets and spiders. The weird fruits are also known as Osage oranges, hedge apples, and monkey brains. The scientific name of the tree is Maclura pomifera, and it is the only living species of the Maclura genus.
The thorny trees were used as fencing along the edges of farms before barbed wire was invented.
Hedge balls apparently are not very good at repelling insects. My own observation is that they do have a smell much like a citronella candle which is used as an insect repellent. It would be a good science experiment for a kid to recheck the Iowa State University results. https://hortnews.extension.iastate.edu/2014/10-24/hedgeapple.html
The wood of the trees is strong and burns well. It was once used by the Osage Native Americans to make bows.
The fruit is nonpoisonous but has a bitter flavor and few animals will eat it although some of the fruits appeared to have been partially eaten. The hedge ball contains a white, thick juice that gives some people a rash. The seeds can be toasted and eaten. Here is a Youtube video of kids tasting the seeds. https://www.youtube.com/watch?v=9UoPIizdWto
The hedge ball is rumored to have some healing properties. https://www.npr.org/2015/12/09/459099506/iowa-chemist-turns-inedible-hedge-balls-into-valuable-cash-crop
