Butterfly chrysalis deformities are not unusual. Some are flaws that are fatal to the adult. If it can emerge, it will be so flawed it either won’t be able to fly or won’t be able to even fully emerge.
The change from caterpillar to chrysalis is a quick change, a total of about three minutes.
To change from a caterpillar to a chrysalis or pupa, the caterpillar literally wriggles out of its cuticle.
The new chrysalis is soft and easily deformed for the first hour after pupating. Anything that touches the soft chrysalis can cause damage. Some damage is natural, caused by twigs or leaves surrounding the soft chrysalis. Other damage is caused by an insect or other critter touching the J’ing caterpillar or soft chrysalis.
Some deformities will never be noticed when the adult butterfly emerges. Other deformities will cause death to the chrysalis or to the adult butterfly.
An improperly placed silk strand can prevent the caterpillar cuticle from moving upward and off of the chrysalis. Chrysalises with this problem will be part caterpillar and part chrysalis. Other problems can cause this same ‘half-and-half’ chrysalis, including insect growth regulator, used for both dog/cat flea/tick medication and as a plant insecticidal treatment.. An adult butterfly cannot emerge from these chrysalises.
In a late instar older caterpillar, the adult wing pads are already formed. After it pupates, the wing pads are loose for the first few minutes. The chrysalis slowly smooths its outside and hardens. In the chrysalis stage, the wings continue to mature. In a few cases, after the caterpillar pupates, the wing pads fall downward before the chrysalis reforms into its species’ shape. These chrysalises will die.
If another caterpillar or insect walks over a soft chrysalis, its tarsi (feet) can puncture the chrysalis’ cuticle. Tiny droplets of hemolymph will ooze from these punctures. The drops turn black as the hemolymph scabs over the punctures. In many cases, the adult butterfly will be normal.
In other cases, the tarsi will create tears in a pre-pupa (j’ing caterpillar) and it will rupture in the wrong place when it pupates, resulting in a severely damaged chrysalis.