Butterfly of the Week: Heraclides Erostratus

This week's butterfly, Heraclides erostratus, is also called the Pale-Spotted Swallowtail or the Northern Black Kite with Pale Spots. It is found in Mexico, Guatemala, and Belize. It's big enough that its always apparently having been rare seems a good thing, but it is now a threatened species.

There are three subspecies. The nominate subspecies, H. erostratus erostratus, is found from Chiapas south to El Salvador. 

Photo by Johnvandort, Honduras, August. Fore and hind wings can move independently.

H.e. erostratinus is found in eastern Mexico.

Photo from Butterflies of America.

Photo from Josesgh, Mexico, August.

Veins can stand out clearly, giving the wings a pleated or ribbed appearance.

Photo from Torres-Sebastian, Mexico, October.

H.e. vasquezae is found in western Mexico.

Photo from Butterflies of America.

None of the subspecies has ever been very common, anywhere, in recorded history. Males, however, don't seem to make themselves hard to see. They are said to roost along the shrubby edges of trails, about a meter above the ground, and fly up as people pass by. 

The Swallowtails were supposed to be named after heroes of ancient literature. Possibly someone who read a reference to Erostratus, or Herostratus or Eratostratus, quickly thought the best known man who used this name was a hero; or perhaps there are other less known men by the same name, one of whom was a hero. The best known Erostratus in ancient Greece was an arsonist who burned a temple for no good reason.

The butterfly has never been all that destructive. It has not been studied in depth, although it appears on many lists. The Citrus it favors are wild trees that grow in forests, typically an an altitude of about 5000 feet (1500m). 

It is a large, dark Swallowtail with only one band of spots around the eds of its wings. Males' spots are sometimes red and yellow; females' are usually white and pink. The butterflies fly all year, with a peak in one month followed by a trough inthe next month suggesting that there may be six generations each year. The highest peak month is August. Males do some composting and are easily photographed at puddles. Both sexes pollinate flowers. 

Caterpillars are said to travel in groups and eat the leaves of trees in the genus Citrus, but do not seem to be a pest or even a nuisance to farmers. These butterflies keep to themselves and give no one else any trouble. Humans should only take a similar attitude to them.