October 6, 2009
Hi Bugman,
Have had a lot of this kind of (butterfly?) this year.  Always shows up at night in either the house or the barn.  Can you identify it?
Thank you,
Costa Rica

Day Flying Moth, we believe

Nothus lunus

Hi Jordan,
Though it looks like a Swallowtail Butterfly, WE actually believe this is a diurnal moth and not a butterfly, but we haven’t had any luck with its identification.  It reminds us of the Sunset Moth, Urania fulgens.

Update from Julian Donahue
This is a moth in the Neotropical family Sematuridae (one species makes it, rarely, into Arizona). This particular moth goes by a number of names, and a revision of the genus is clearly needed. It is most likely Nothus (= Sematura) lunus (or aegisthus?), which occurs from Mexico to Brazil. There are anywhere from four to 11 recognized species in the genus, which also occurs in the West Indies.

Update from Karl
Hi Daniel:
This is indeed a moth, Sematura luna (=lunus?), and it looks like it is probably a male (females have a white band down the middle of both wings). The taxonomy is a little confusing as I had trouble determining if luna = lunus, or if they are closely related species or subspecies. My favourite Costa Rican reference (Mariposas de Costa Rica) uses S. luna, South American references seem to use S. lunus. It belongs to the relatively small and poorly understood family Sematuridae (subfamily Sematuerinae), which has approximately 40, mostly neotropical species. They belong to the superfamily Geometroidea, along with the Uraniidae and Geometridae families. Although they resemble the large diurnal Uraniid moths, most Sematurids are nocturnal, Sematura sp. included. They are sometimes called Eyetails, for obvious reasons. Regards.

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