Cafe con Leche in a Mexican Forest: a Rare Hairstreak Makes a Guest Appear- ance in Mexico

by Jeffrey Glassberg and Robert K. Robbins noted at this site included orange kite-swal- lowtail (Ewytides thyastes), black-barred On July 24, 2005, Glassberg was butterflying cross-streak (Panthiades phaleros) shining between Palenque and Bonampak, just east of grayler (Menander menander), white-patched Chancala, in the southernmost Mexican state heliconian (Heliconius sapho), white-edged of Chiapas. A hairstreak flew down from the red-ring {Pyrrhogyra otolais), beautiful trees and perched on a leaf about 3 feet above beamer (Phocides belus) and great bent-skip- the ground. At a distance of about 12 feet, two per (Ebrietas osyris) photographs were taken before the hairstreak Thereus lausus was discovered more than flew off. 125 years ago and occurs widely in lowland Because of its very distinctive pattern, forest from southern Brazil to Belize (recent which can be confused with no other Central report) and now Mexico (this report). How- American hairstreak, the butterfly was thought ever, little is known about its biology, prob- to be a cafe-au-lait hairstreak (Thereus lausus), ably because this is exceedingly rare. even though this species has not been previ- The caterpillars of close relatives in the ously reported from Mexico. Subsequent Thereus eat mistletoes (plant Loran- examination of the photographs confirmed thaceae), and males occupy mating territories this to be a female cafe-au-lait hairstreak. A along forest and shrub edges in the early female collected by William Schaus in Gua- morning before about 9:00 am. It is likely that temala more than a century ago (now in the cafe-au-lait hairstreaks share these biological collection of the Smithsonian Institution and traits. The English name refers to the under- shown below) has the same color and mark- side pattern, with swirling white on a dark ings, but is markedly faded. Other species brown ground color. s

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47 Glassberg, J. & R. K. Robbins. 2005. Cafe con leche in a Mexican forest: a rare hairstreak makes a guest appearance in Mexico. American Butterflies 13 (3): 47.