The challenge is for children aged four to 11 and the aim is to read six books over the summer period before the closing date of this Saturday (Sep 11).
Wild World Heroes aims to educate youngsters on what we can do to make a difference to the environment and stand up for the planet.
More than four and a half thousand children across the county have signed-up, and those who have started are being encouraged to read those last few books.
Read this: Memorial bench for man who started Whitby Folk WeekCounty Cllr Greg White, Executive Member for Libraries, said: “It has been wonderful to see so many families enjoying being back in the library this summer.
"The challenge is great in helping children keep up their reading skills over the school holidays and library staff have helped many youngsters to discover new authors or subjects which has fuelled their enthusiasm for books.
“Staff and volunteers are always happy to help children find something they will enjoy reading so don’t miss out on this last chance to be a Wild World Hero and collect your well-deserved medal.”
You can check library opening days and times here.