How much wing can a butterfly loose and still fly?

Pale swallowtail butterfly in my garden, taken with my iPhone 15 Pro.

Like most insects (except true flies), butterflies have four wings.  Although they appear to only have two, each side is actually equipped with a pair.  You can see it more clearly on the butterfly I photographed a few years ago while visiting Palm Springs.

Checkerspot butterfly photographed in 2023.  Notice there are four wings.

The forewings are the most important in flight; the hindwings are less important and can take a moderate amount of damage before rendering a butterfly flightless.  Many butterflies, like the swallowtails, have small projections coming off the rear wings that can be sacrificed to help facilitate escape from a predator.

While a butterfly may be able to fly with less than 50% of its original wing area, a more important consideration is a balance between both sides.  If the hindwings are both totally removed, a butterfly may still be able to fly.  However, if the left or right side is severely damaged, it is likely to render the insect flightless.  

Butterfly wings are made out of chitin, a stiff but flexible protein that an insect's exoskeleton is made of (same as in shrimp, our fingernails, and much of our hair).  The chitinous fabric making up the wings is not alive, and there is no ability for a butterfly to repair damage done.  However, butterflies in captivity may have their wings repaired.  There is an interesting video here about a woman who repaired the wing of a monarch butterfly.  It was eventually able to fly.

Since they can't afford it, we could open a butterfly wing repair station (butterflies can't read, so we would have to put up graphic signs for them) and help butterflies that have such issues.  Moths would also be welcome, but we would have to draw the line somewhere, so other insects would have to be banned.  The problem with this, of course, is that flightless butterflies would have trouble getting there, so we would need a transportation service, like Ubers for Lepidoptera (UL for short).  They wouldn't need a full-size car, maybe just a scooter equipped with a plastic box to house the ailing insect during transport.  

Any volunteers?

Thanks for reading.

Eric Svendsen     www.ericspix.com