Mexican Yellow (Eurema mexicana) life history
Mexican Yellow (Eurema mexicana) Life History

Eggs, 12-10-13

Recently emerged, 12-11-13

First instar, 12-14-13

Second instar, 12-17-13

Third instar, 12-22-13

Fourth instar, 12-29-13

Fifth instar, 1-06-14

Prepupal caterpillar, 1-08-14

Chrysalis, 1-11-14

Pre-emergent chrysalis, 1-24-14

Fresh adult Mexican Yellow, 1-25-14

In south Texas, the primary host plant for Mexican Yellow is Prairie Acacia, Acacia angustissima. Since I have been unable to find local populations, I began trying to grow the shrub from transplants and from seeds. After several false starts (the plants are sensitive to over- as well as under-watering, and popular with our rabbits), I finally got a couple of plants established in pots. And I was delighted when I discovered one of the plants covered with nearly 2 dozen eggs from a Mexican Yellow. The next day, I was chagrined to find that a rabbit had eaten most of the fresh growth AND most of the eggs. Even herbivores are threats to butterflies! Fortunately, a few eggs were spared, and I was able to raise two caterpillars, as well as observe later generations "in the wild."

As with many sulphurs, the hatchlings were yellow, and they turned green as they began feeding. The face remained tan until the third instar. The amount of red on the spiracular stripe of the fifth instar is highly variable. Some caterpillars have wavy cream lines extending from the spiracular stripe to each leg. The pupa may be speckled with brown (as pictured on this page), or may be entirely green.

Mexican Yellows are most often seen in winter in this area, and this study took place in December-January. The caterpillar took a full month to go from egg to pupa, and the adult did not emerge for another two weeks. Cool weather probably contributed to the slow development.

Mexican Yellow Page