Portland, Ore., comics creator Jonathan Case writes for all ages. He created two Over the Garden Wall volumes with artist Jim Campbell and graphic narratives including The New Deal and The Green River Killer. In his new middle grade comic Little Monarchs, he blends butterfly facts and futuristic fiction. Set in the year 2101, Little Monarchs introduces 10-year-old Elvie and 44-year-old biologist Flora, who track the West Coast monarch migration in a rugged all-terrain van. Solar radiation has poisoned diurnal mammals, and Elvie and Flora survive thanks to a milkweed-derived remedy, collected (gently) from monarchs’ wings. They’re on a quest to create a “sun sickness” vaccine and reunite with Elvie’s parents, who followed the butterflies to Mexico. We spoke on the phone with Case during his northwest U.S. book tour (where he gave out native milkweed seeds with every signed copy), before he and his family started an off-grid Utah adventure. He shared his thoughts on outdoor appreciation, threatened species, and crafting imaginative fiction with an environmental consciousness.

How did you develop the 22nd-century setting of Little Monarchs?

It actually began in the realm of fantasy, with references to the present day. The more I worked on it, the more reality rose to the top. You can visit all the places the characters travel to in the book. But I wanted there to be a heightened element, giving a girl free rein on an open geography where she could explore without the dangers of other people or natural predators.

Do you see those unpopulated spaces as threatening or as liberating?

I’ve always liked those small moments in books like The Road where the characters get to relax and explore. Yet there’s definitely a darkness you can’t escape. Anytime you write a book that takes place after the Fall of Man, you will have that tension! Civilization has receded. It’s kind of a neo-Western.

Why did you develop this survival story for middle-grade audiences?

I started [writing Little Monarchs] right before I released my first book in 2010, and [it became] a passion project. I work in an office most of the time. I wanted to do a book grounded in reality so I’d have to go out and learn new things that are fun to impart to kids.

That’s why it’s comics, too. Early on I had the vision of taking coordinates and compass headings, mapping the story onto real geography. Comics are an easy way to communicate ideas like star navigation and knot-tying to children and adults.

What research did you do on monarch butterflies to create this book?

We live a little south of Portland, so we live proximal to the migration. A convenient touchstone, the Xerces Society, is based in Portland, and they’re among the main preservationist organizations for invertebrates. They were a resource in terms of pamphlets and access to naturalists I could pester with questions. Meeting naturalists at the bigger monarch groves was helpful too. We happened to visit a grove on the Day of the Dead, and to see the butterflies clustered like that, having found their way, it’s a miracle. They do have something to tell us about eternity and connection with the people we might have lost.

Your protagonist, Elvie, is a Black tween, a brave traveler, and a science whiz. How did you develop this confident character?

She came to me that way pretty early on. Because this book started 12 years ago, the landscape was a little different in publishing, and there were not as many diverse characters. But I grew up with a lot of mixed-race families with adopted kids, and you just didn’t think too much about it when you went over for a playdate. Elvie helped me describe a family that’s thrown together by circumstance [Flora, the scientist, is white, and she and Elvie meet diverse groups on the road]. She’s named after a Haitian friend, Elvie Bazilme; I’ve done some medical relief in Haiti, working in a pharmacy, filling prescriptions, and Elvie is an incredible person who helps with running the Haiti Foundation for Hope in Terre Blanche.

Little Monarchs includes a boy, Otis, named after your late son. Elvie says his name backward as “Sito.” If you are comfortable talking about it, can you say how you made the difficult decision to bring Otis into the book?

Thank you for asking. I don’t mind talking about it, in fact. My son died when he was two from seizure complications. In my grief process, in spite of people telling me “you’ll never forget,” I just knew I would start to lose connections. At a certain point I decided to include him in a kind of reversal of fortunes: In the book, he has lost his family. In reality, his family had lost him. And with the book, I got to continue on with him a little longer. I could incorporate the way he spoke, the little phrases, the little half-formed words he liked to say. It became a monument to him.

You acknowledge your two daughters, now ages 10 and 4, as catalysts too. How has your environmental messaging changed as a result of parenting?

My wife said this: first it was a book for the children I didn’t have, then it was a book for the children I did have, and then it was a book for the child I lost. Throughout the process, that has been with me.

I think everything starts with relationship, and I want children to join in on the overall dream of engagement with the world around them. Kids recognize that the world needs help, and they notice the small details that adults miss. That’s why this book isn’t focusing on some epic war, but on creating citizen scientists who can restore what the monarch migration used to be.

What are you working on now, and will Little Monarchs have a sequel?

You dedicate a decade of life to something, and you come out of that and think, “What now?” In the course of writing this, I found a happy roundness to the story and I could see it as being one book. But I have ideas about where Elvie and Flora and the rest of the characters will go. Right now, my next book might be a picture book focused on humor and resilience in childhood. I’m rejiggering my creative brain.

Little Monarchs by Jonathan Case. Holiday House/Margaret Ferguson, $22.99 Apr. ISBN 978-0-8234-4260-7