Butterfly Chrysalis Deformities

Many butterfly chrysalises have deformities that never make a difference in the adult butterfly. The other deformities cause minor issues, serious issues, or death.

Monarch butterfly chrysalis with antennae, legs, wings, abdomen, proboscis, brushfeet, and legs labeled

Monarch butterfly chrysalis
with antennae, legs, wings,
abdomen, proboscis, brushfeet,
and legs labeled

Monarch chrysalis labeled; wings, antennae, legs, proboscis, and abdomen

Monarch chrysalis labeled;
wings, antennae, legs,
proboscis, and abdomen

Monarch butterfly chrysalis with legs, wings, abdomen, and antennae labeled

Monarch butterfly chrysalis
with legs, wings, abdomen,
and antennae labeled

Giant Swallowtail chrysalis with wings, proboscis, antennae, and legs labeled

Giant Swallowtail chrysalis
with wings, proboscis,
antennae, and legs labeled

One antenna of this Monarch chrysalis is bent backward.  The adult butterfly emerged with the antenna bent .

One antenna of this
Monarch chrysalis
is bent backward.
The adult butterfly emerged
with the antenna bent .

Monarch chrysalis pupa cocoon with a split proboscis

Monarch butterfly chrysalis
with a split proboscis

A milkweed stem pressed into the wing portion of this Monarch chrysalis.  The adult chrysalis had a dented wing with missing scales in the exact same area.

A milkweed stem pressed
into the wing portion of
this Monarch chrysalis.
The adult chrysalis had a
dented wing with missing
scales in the exact same area.

A tear in the wing of a chrysalis means a tear in the adult butterfly's wing

A tear in the wing of a
Monarch butterfly chrysalis
means a tear in the
adult butterfly’s wing

Monarch butterfly chrysalis missing a tarsus.  The adult butterfly is also missing the tarsus.

Monarch butterfly chrysalis is
missing a tarsus/foot.
The adult butterfly is
also missing the tarsus.

A Monarch chrysalis is missing its right brushfoot leg and right middle leg.

A Monarch chrysalis is
missing its right brushfoot
leg and right middle leg.
The adult is missing the
same two right legs.

A Monarch chrysalis is missing its tarsal claws.  The adult butterfly is also missing the claws and cannot hold on with those two legs

A Monarch chrysalis is missing its tarsal claws. The adult butterfly is also missing the claws and cannot hold on with those two legs

This chrysalis wing section is wrinkled.  The adult butterfly has a wrinkled wing and is missing scales on that wing.

This chrysalis wing
section is wrinkled.
The adult butterfly has a
wrinkled wing and is
missing scales on that wing.

Gulf Fritillary butterfly missing two legs

Gulf Fritillary butterfly
missing two legs

Gulf Fritillary butterfly missing two legs

Gulf Fritillary butterfly
missing two legs
falls forward when it leans
to drink from another flower

Gulf Fritillary butterfly missing two legs

Gulf Fritillary butterfly
missing two legs

How serious are deformities in butterfly chrysalises?

With the thousands of Monarch chrysalises we raise every week, we occasionally see deformities. A study of these deformities revealed which deformities are serious enough that the chrysalis should be euthanize and which are safe to release into nature. We do not like to euthanize a butterfly unless it is necessary.

When a caterpillar is a few days from pupation, it already has adult legs, wings, proboscis, and antennae. Once it pupate, these body parts continue to form and mature.

Many chrysalis deformities are caused by one or more of these parts being moved out of place. If the misplacement isn’t serious, the adult will emerge with the expected deformity: missing legs, bent wings, crooked antennae, or other abnormal parts. If the misplacement is serious, the chrysalis either dies or, when it is time, the adult butterfly cannot emerge.

We decided to see the seriousness of different flaws in chrysalises. We wrote a number or letter on a plastic cup lid, laid the chrysalis on the lid, and took a photograph. The chrysalis was glued to the bottom of the lid. The side and bottom of the cup were lined with paper towel. The adult butterfly emerged and was placed in a special envelope and the cup number written on the envelope. Later that evening, after work was finished, the adult butterfly was compared to the chrysalis photo. A photo was taken of the adult butterfly and placed with the chrysalis photo. Before long, we were able to tell if a chrysalis had a serious deformity.

Some of these images are two images in one. To see each one clearly, please click on the image.

Some chrysalises looked normal except for a tiny mark on the proboscis area, but the adult butterfly would have a split proboscis. A split proboscis means that a butterfly cannot drink and will starve to death.

Others were clearly missing the tips of the legs, the tarsus (foot), the tarsal claws (hooks on the tips of the ‘feet’), had deformed or misshapen wings, misshapen bodies, bent or missing legs and/or antennae, and many other types of deformities.

Over the years, we have learned when we should euthanize a chrysalis and when we should allow the adult to emerge as a beautiful healthy butterfly.

One year, before we did this study, we saw a Gulf Fritillary butterfly in the garden. It was sitting on a zinnia bloom, drinking from the tiny yellow flowers. Every so often it would fall on its face, wings outstretched as if to catch itself. After taking photos of it doing this over and over, we picked up the butterfly only to discover that it was missing two legs. No wonder it had problems. But even with these problems, it continued to fly around the garden, drinking nectar from flowers as it landed and flew away again.

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