Starr County Butterflies
A fresh egg, 11-25-21
A developing egg, 11-27-21
First instar
Second instar
Third instar
Fourth instar
Fifth instar
In position to pupate
Chrysalis
Fresh adult Statira Sulphur before release 12-21-21. Photo by NBC employee Stephanie Lopez.
In November of 2021, Linda Cooper saw a Statira Sulphur ovipositing on Guamuchil (Pithecellobium dulce) at the National Butterfly Center in Mission, Texas. She obtained permission from the authorities for me to collect eggs and raise the Sulphurs, on the conditions that I write an article about the experience and that I release the adults at the Butterfly Center. As it turned out, I unexpectedly had to leave town shortly after the caterpillars pupated, so I returned chrysalids instead of adults, and the employees of the center released the adults. The article was written and appeared in the American Butterflies magazine (Vol 30, No 4 Winter 2022). Below is a brief overview of the adventure.
Guamuchil has not previously, as far as I can tell, been reported as a host for Statira Sulphurs. On the other hand, it is a well-known host for Large Orange Sulphurs (as well as Pixies and numerous moths). The eggs of the two Sulphurs proved inseperable to me, even under magnification, and I was concerned about confusing the 2 species as I reared the caterpillars. Providentially, while we were collecting eggs, we observed another Statira ovipositing. This allowed us to secure some eggs of certain identity (fresh eggs are white, while older eggs turn yellow).
The caterpillars matured very quickly, molting every other day through the first 4 instars; they pupated just two weeks after emerging. The caterpillars were very sensitive to the condition of the food; they could eat only the freshest, tenderest leaves, even in later instars. I realized this when I noticed the older caterpillars were tearing rather than chewing the leaves I was feeding. Fortunately, the plant is common in the Roma area, and I was able to find adequate tender leaves to finish them out.
 Face of Statira Sulphur |
I isolated 4 caterpillars for photos. The extras were not carefully observed. As it turns out, one of the "extras" was a Large Orange Sulphur. Only in the last instar was it evident to the unaided eye that the caterpillar was a different species. In the final instar, Statiras have dark, pointed setal bumps (see in the picture of the face) the give the body a rough, speckled appearance. The Large Orange Sulphurs, on the other hand, have a uniform, velvety appearance. This difference is already present in the fourth instar, but probably not evident to the unaided eye.
2021 was a year that Texas and northern Mexico saw a heavy freeze in February. The cold caused the Rio Grande Valley's Guamuchil trees to die back to the ground. Many these grew out from the roots in a bushy shape with very rapid growth. It is my suspicion that the freeze benefited the Statiras: it reduced or killed off potential competitors, and the re-growth of the host from the roots provided far more fresh leaf material than is normally present. This probably opened the door for the wide-ranging Statira Sulphurs to at least temporarilly colonize the Guamuchils in the RGV.
Many thanks to Linda Cooper, Dr. Glassberg and Marianna Wright, Stephanie Lopez, and the others who made this study possible.