Although butterflies seem fragile, they are more robust that you would think. Monarchs migrate 3,000 miles. Nevertheless, their lives are short and wings do wear out.
It's surprising how well a monarch can fly with a tattered wing, even when missing up to half the wing. It's common to see a large triangular gap in the rear wing where a bird attacked but the butterfly escaped.
But when the main "spar" of the front wing breaks close to the body, it's "game over" for the butterfly. When this happens to one of my captive breeders, I attempt a repair. I've been successful three out of three times.
In the photo, can you see the "splint" on the wing, visible just under the window of the house?
Male #5 broke his right wing close to the body. I glued a "splint" to the broken spar on the leading edge of the wing. The splint came from the dried stem of the seed head of a small grass plant. The stem was dry, stiff, hollow, and light. I used a fast-drying glue, but not too fast.The biggest problem was immobilizing the butterfly while I worked. Number 5 was tired from struggling with his broken wing, so remained immobile while I worked until the glue dried. More recently, I have placed injured butterflies in the refrigerator for half an hour, which reduced their struggling substantially.
After the operation, I placed him in the sun on a flower to recover--perhaps to feed--and for the glue to dry. When I came back after an hour, he was still there.
I wanted to test the repair, so I tossed him into the air. He took flight, steadily gaining altitude until he was halfway up into a large maple tree. There he landed in the foliage. Monarchs spend the night in trees, so I presumed the repair was successful and he was good for a few more miles and matings.
Here's a wing problem that didn't need repair. In 2025, I captured a female I found in my garden laying eggs.
She was missing most of her two hind wings--in a pattern that suggested attack by a bird. Nevertheless, she was able to fly strongly and precisely. This raises a question: What is the function of the hind wings... if a butterfly can fly so well without them? After all, flies have only one pair of wings. And other kinds of insects like ants/bees/wasps have two pairs of closely-linked wings that act as one pair.
I haven't heard of rehabilitation of insects, although it's common for mammals and birds. When I worked some years ago at the International Crane Foundation, I saw avian vets work wonders with injured cranes.
Collision with power lines was the most common cause of mortality in adults of endangered whooping cranes. An injured whooper would be flown the Crane Foundation or the National Wildlife Health lab in Madison. There vets would perform surgery on terrible compound fractures of delicate wings. Special instruments were used to hold the mending wing in place. This was care equal to what a human might receive in intensive care.