Calliandra, Blue Butterflies & Ants (part 4)

(click on photo to enlarge)

After several weeks of dining on Baja Fairy Duster (Calliandra californica) flower parts, the caterpillars reach the last instar stage. From a mere speck on the plant, they have grown to an average of 13 mm. Eating ceases. Chemical changes are taking place inside and the caterpillars begin to wander about looking for a safe place to pupate. After a period of inactivity (at least outwardly), the body begins to pulsate and the the skin splits. What we have known as the caterpillar now morphs into a smooth, somewhat waxy looking pellet called the chrysalis. Inside this structure is where the magic happens. If the caterpillar was healthy (no bacterial, viral or parasitic infection) in a week or so, a butterfly will emerge.

Last instar measuring about 13 mm, Ceraunus Blue (Hemiargus ceraunus)

Fresh chrysalis with shed skin, Ceraunus Blue (Hemiargus ceraunus)

A sign that the butterfly is about to emerge is the darkening of the chrysalis which occurs approximately 24 hours before the butterfly ecloses. Notice how you can see the wings and how the male’s wings are a much brighter blue.

Mature chrysalis of a female Marine Blue (Leptotes marina)

Mature chrysalis of a male Marine Blue (Leptotes marina)

In the next and final post in this series, the butterflies will be seen eclosing from their chrysalids.