Wednesday, January 21, 2009

What is Going On Inside a Monarch Chrysalis?

There is a lot of action going on inside a Monarch butterfly chrysalis.

We assume that the inside is just 'mush' but it isn't mush. It is soft and tender and easily damaged.

A large caterpillar already has wings - so to speak. They are called 'wing pads' and are already growing into wings. (Swallowtail caterpillars can be identified by the wing pads alone when the wing pads are viewed under special lights.)

This freshly pupated Monarch chrysalis is labeled. Wings, proboscis, legs, eyes, and antennae are clearly identifiable at this stage.  (The arrows are slightly inward for the eyes in this photo.  The eyes are a little lower and further out.)

The proboscis is seen as two lines. These two lines are two tubes that are forming. When the adult butterfly emerges, the proboscis is two tubes that the adult must fuse together into one proboscis.  They zip together and create a channel between the two; the channel is the 'straw' through which the butterfly drinks.  Each side of the proboscis is a 'tube' that has blood flow, nerves, trachea, muscle, and more.

The chrysalis cannot see although the eyes are also forming.

As a caterpillar changes into a chrysalis, it is extremly active. Some species of butterfly chrysalises are super active, moving every time something touches it. Red Admirals and Painted Lady chrysalies are notorious for their activity in their chrysalis stage. 'Mush' doesn't move - it requires structure to move in a co-ordinated fashion to first, work the cremaster tightly into its silk pad and knock off its old skin and two, to knock off or discourage parasitoids and predators.

As the chrysalis changes shape and hardens, these parts are less visible. Although less visible, they are still clearly identifiable.

Parts of a Monarch pupa chrysalis identified

If a soft, freshly pupated chrysalis falls, some of its organs can be seen in the resulting 'splat'. Yes, a fall kills a soft chrysalis.

In most cases, a hardened older chrysalis can fall for several feet without damage. If the emerging adult butterfly is not on a smooth surface and can obtain a grip on something wtih its feet and climb up on something to hang (to expand it's wings), it will also live and become a normal adult butterfly.

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