How To Euthanize Crippled Butterflies

The choice of whether to euthanize or not to euthanize is a personal one. Although we won’t make that choice for anyone, many people have asked us the best way to euthanize a crippled or diseased caterpillar, chrysalis, or butterfly.

Monarch butterfly with chrysalis shell stuck on its head

Monarch with chrysalis shell
Stuck on its head
Even when removed
Proboscis cannot work
Butterfly cannot eat

On this page, the term ‘butterfly’ will refer to an egg, caterpillar, chrysalis, or adult butterfly. After all, they are all butterflies. They are simply in different stages of their lives, from ‘child’ to adult.

The most common method to dispatch a butterfly is by placing it into a freezer.

Most people cringe and shy away from the quickest and most humane method simply because it feels the most cruel and gives most of us the heebie-jeebies. Instant death is the most humane. A quick stomp of the foot and the butterfly is dead – INSTANTLY. Few people can handle dispatching one that way. on an emotional level, it ‘feels’ inhumane. Another reason many people shy away from this method of disposing of a crippled butterfly is because of children. Stepping on a butterfly can give the wrong message to any young watching eyes that may not be old enough to understand the kindness of a quick and instant method of euthanizing a butterfly that is crippled and cannot live.

Most people choose to place the butterfly into an envelope or container and into the freezer. The butterfly normally dies within 10 or 15 minutes. It lowers the body temperature and, basically, the butterfly simply ‘goes to sleep’. It certainly helps all of us to remember that butterflies do not feel pain.

Painted Lady in glassine WRONG with open wings

Painted Lady in glassine envelope
Open wings is WRONG position
Wings should be closed

Monarch butterfly in glassine envelope

A Monarch butterfly
Properly position in envelope
Wings folded behind back

Although butterflies do not feel pain, we recommend placing an adult butterfly in an envelope when placing it in a freezer. Its wings should be folded behind its back, in its normal resting position. If its wings are open, it will struggle to close them. Just as we rest with our arms lying by our sides, butterflies rest with their wings folded together behind their backs. Open wings is comparable to humans holding their arms above their heads – it is not a natural resting position.

If the freezer isn’t set on colder settings, it may take longer. We recommend leaving the caterpillar/chrysalis/butterfly in the freezer overnight.

Others have chosen to flush a caterpillar or chrysalis down the toilet. We prefer the freezer or stepping on the butterfly because they can be under water for quite a few minutes without dying. We have seen chrysalises live after being under water for 15 minutes. Caterpillars can often be revived after ‘drowning’ in the water holding their host plants in a rearing container.

For many of us, euthanizing a crippled butterfly is a difficult emotional choice. For some people, it is the hardest part of raising butterflies. We don’t raise them to kill them. We hope that this page makes the choice of euthanizing a bit easier for those of us who find it difficult.

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