You ask how rare is it? Well no butterfly in this family had been seen in the United States in over 100 years, this was a first US record. The range for this butterfly is usually 300 miles south of the US border in Mexico. It remained at the park for two and a half days before leaving.
Also Texas Parks and Wildlife magazine ran this article:
Butterfly Fever
With butterfly-friendly flora popping up all over South Texas, rare beauties are becoming easier to find.
By Karen Hastings
When North Carolina photographer Randy Emmitt traveled to the Lower Rio Grande Valley of Texas last December to expand his rare butterfly portfolio, he never expected just how successful the trip would be.Emmitt knew subtropical South Texas was the place to find uncommon butterfly species, but what he found was even better: a dainty beauty with transparent wings - a thick-tipped greta (Greta morgane) - that had never before been seen in the United States. "The day I found it, I was hanging out with the local butterfly folks. Everybody had just left, and I was heading to the car and taking a last look at the flowers."
The mystery clearwing was dancing along the golden eye daisies outside the World Birding Center headquarters at Bentsen-Rio Grande Valley State Park. Emmitt quickly grabbed his cell phone and, within minutes, a crowd of 10 local butterfliers had returned to share his find.
"Somebody said it was 100 years since any (clearwing) had been found in the United States," says Emmitt. "I didn't expect something so big and so beautiful to show up, and yet be so unique. It just happened to be my luck."
Luck indeed. Emmitt had wandered into a butterfly phenomenon that unfolded across the Lower Rio Grande Valley last fall: Six different U.S. record species were reported in 52 days in one county at the southern tip of Texas.
The full article can be found here.
