Butterflies do all their growing in the caterpillar stage. An adult butterfly is fully formed, cannot grow and doesn’t really heal. If you find a butterfly with a broken wing, the insect is probably never going to fly again. The butterfly can, however, live. If the butterfly is female and has already mated, she might even lay eggs, which you can raise when they hatch.
Fixing the Wing
An entomologist with access to laboratory materials and delicate tools might be able to fix a butterfly's wing, possibly even enough for the butterfly to fly. You’d probably just do more damage if you tried, though, so it’s best not to. If you are determined to help the butterfly, simply catch her and take her inside. Catch her by placing a glass over the top and sliding a piece of paper underneath. Turn it over slowly so the paper is now on top and take the assembly inside. Put the glass somewhere out of direct sunlight. Swap the paper for a piece of kitchen towel or even unscented toilet tissue, and secure it with an elastic band -- you need to keep the butterfly contained while you set up suitable housing.
Housing the Butterfly
The butterfly needs accommodation that contain things to climb up that don't allow too far of a fall. The simplest option would be a cardboard box with muslin secured over the top with a large elastic band. A large plastic storage box, ideally a transparent one, again with muslin over the top, is another option. Add a couple of twigs for the butterfly to climb up and perch on. The key thing is that she can’t fall more than a couple of feet. The larger a body the butterfly has, the more important this becomes. A butterfly with a small body could fall a long way with no damage; but one with a larger, fatter abdomen could hurt herself.
Food for the Butterfly
Check the needs of your species, but most are fine with an artificial nectar solution. Mix plain white sugar -- not brown -- with water in a pan, preferably a glass one, at the ratio of about 1 part sugar per 10 parts water. Heat gently and stir continuously until all the sugar has dissolved. Let the mixture cool before soaking one or two cotton balls in it and placing them on a small saucer in the butterfly’s house. If the butterfly won’t feed, very carefully slide something extremely thin, such as a toothpick, into the middle of her coiled proboscis -- her tongue -- and pull down gently to uncoil it, nudging the end into the food. She should start sucking up her dinner.
Food for Offspring
If the butterfly came from the wild and is not obviously male -- some species show clear differences in wing color and pattern between the genders -- she possibly has mated before breaking her wing. This means she’ll have eggs to lay. Be prepared: Confirm the food of that species in caterpillar stage, and collect a few stems or twigs with leaves on. Wrap the bottom of the stem in cotton balls soaked in plain water and cover it with plastic cling wrap to keep the plant material fresh. Place it in her house. If she lays eggs, transfer the leaves with eggs to another container. The eggs should hatch into very small caterpillars, which need just a steady supply of the appropriate plant material and something to pupate from, which may be the branch the creatures fed on.
Judith Willson has been writing since 2009, specializing in environmental and scientific topics. She has written content for school websites and worked for a Glasgow newspaper. Willson has a Master of Arts in English from the University of Aberdeen, Scotland.