Cassius Blue (Leptotes cassius) life history
Cassius Blue (Leptotes cassius) Life History

Cassius Blue flying to host plant, 7-13-11

Female ovipositing, 7-13-11

Egg, 7-13-11

New caterpillar, 7-15-11

Young caterpillar is looking for fresh food, 7-17-11


Once again looking for fresh food, 7-23-11

Last-instar caterpillar, 7-26-11

Caterpillar shows its long neck and black head, 7-27-11

Prepupal larva has pinkish color, 7-28-11

Chrysalis, 7-30-11

Fresh adult Cassius Blue, 8-4-11

This study began when I observed a female Cassius Blue ovipositing on Mexican Orchid Tree, Bauhinia mexicana.  As is often the case with Blues, the fresh eggs at first appeared to be very pale green; later, they appeared white. I collected three eggs and, I later discovered, a couple of young caterpillars. From the eggs, two of the emerging caterpillars were raised successfully.

The eggs eclosed two days after being deposited. The tiny early-instar caterpillars proved to be very active crawlers. It seemed they were most active when they decided they wanted fresher food, which was often! (My original plan to was keep each caterpillar on its original flower head for at least a week, as the branch was placed in a cellophane-covered vase to keep it fresh. Unfortunately, the Orchid Tree flowers did not last long when cut, and the larvae seemed to be very picky about the freshness of their food.) I resorted to providing each tiny caterpillar with a single fresh bud once or twice a day as needed. Also, a leaf or two from the host plant were kept in the container to help maintain humidity. The caterpillars showed no interest at all in the leaves. Flower blossoms, when available, seemed to be preferred over the buds.

A curious characteristic of the Cassius Blue caterpillar is its long neck. The other blues and hairstreaks I have raised rarely extend their heads. The Cassius cats liked to stick their necks out, so to speak, much more frequently. The July 27 picture shows the head, but I often saw the neck stretched much further.

Early in the study, when I saw that the Orchid Tree flowers did not keep well, I became concerned that my single tree might not provide enough food. I looked around for another food source. I have the well-known Cassius host, White Plumbago, in my yard, but it was not blooming. I finally offered the larger caterpillars flowers from Powderpuff, Calliandra emarginata, because it had been host to Marine Blue. The caterpillars readily accepted the new host. Having observed that Marine and Ceraunus Blue larvae absorb the red pigment of the Powerpuff flowers when they feed on it, I was curious to know if the same would happen with Cassius Blues. The older caterpillars did get a bit darker, but were still green. When the younger caterpillars were just 4 days old, I also switched one of them to this plant. Even in this case, unlike its cousins, the caterpillar never had any red markings. On the other hand, regardless of host food, all of the prepupal Cassius larvae became a pink or mauve color.

Growth was fairly rapid. The pictured caterpillar pupated after 14 days, and the adult emerged 7 days later. The time elapsed from egg to adult was 23 days.

Incidentally, I have not found Bauhinia mexicana listed as a host for Cassius Blues, but it is very popular with them, at least in the Rio Grande Valley. For example, they are abundant and regular users of the numerous Orchid Trees planted along the famous "wall" north of Bentsen State Park. The wall is the most reliable spot I know of in the Rio Grande Valley for locating Cassius Blues.

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