Field of Science

Colour vs Crypsis

The southeast Asian Lyssa zampa, a large nocturnal uraniine. Photograph by Alexey Yakovlev.

Even if you don't know much about insects, you've probably been taught the difference between a butterfly and a moth. Butterflies are ornate, colourful and active during the day, while moths are... ornate, colourful and active during the day?

A cryptic epiplemine Crypsicoela subocellata, photographed by Stephen Luk.

The Uraniidae are a family of about 700 species of mostly pantropical moth. The family is united primarily by their distinctive sexually dimorphic tympanal organs: in females, the tympanal organs open ventrally on the first abdominal sternite (as in a number of other moths), but in males they open dorsally or laterally at the junction of the second and third segments (Scoble 1995). About 600 of the 700 species of uraniid are assigned to the subfamily Epipleminae, and are generally nocturnal, brown and cryptic. Many epiplemines roll their wings up when at rest, so that they resemble a small brown stick.

The South American migratory Urania fulgens. Photo from here.

However, some members of the subfamily Uraniinae have become diurnal. These diurnal species have brightly iridescent wings with prominent tails, and have often been compared to swallowtail butterflies. One of the best-known species is Urania fulgens, a South American species that migrates north into Central America at certain times of year. Migrating individuals may reach as far north as the southern United States.


Scoble, M. J. 1995. The Lepidoptera: Form, function and diversity. Oxford University Press.


  1. Christopher, a question from a vertebrate-o-centric palaeontologist. When we speak of moths being "male" or "female", are those concepts actually homologous with the same terms as used for vertebrates, or are they merely analogous, having evolved separately? Presumably male and female plants are so named only by analogy?

  2. The current line of thinking, I believe, tends towards the view that sexual reproduction probably originated before the eukaryote MRCA, as the vast majority of eukaryotes reproduce sexually at some point. That said, 'sexual' doesn't necessarily imply 'male and female'. 'Male' and 'female' just refer to which gender produces smaller vs larger gametes, and many organisms (such as fungi and many unicellular eukaryotes) reproduce sexually without any morphological distinction between gamete types. Based on their relative phylogenetic positions, I would guess that plants and animals both evolved separate gamete forms independently (I forget the arguments as to why it would be advantageous to do so, at least for complex organisms, but they have been proposed). All animals have distinguishable sperm and ova, but the earliest animals were probably hermaphroditic. I believe that there are many examples of separate sexes evolving from hermaphroditic ancestors, and vice versa, but I can't remember specific examples off the top of my head (it'd probably be more worthwhile to look for studies on such things among plants, as I think they may be particularly labile in this regard). I don't know of any unequivocal examples of sexual reproduction re-evolving in a eukaryote lineage that went totally asexual, though I think such a thing may have been suggested as part of the evolution of astigmate mites (mostly sexual) among oribatids (mostly asexual).

  3. So, to sum up: arthropod and vertebrate sexes probably are homologous on the level of separate male and female gametes, but quite probably homoplasious on the level of individually separate genders.

  4. Thanks, Christopher, really helpful!

  5. Christopher,

    Are the pharyngeal arches in vertebrates homologous to the first pair of true legs in insects? Are the abdomenal prolegs in holometabolous caterpillars homologous to the ventral mammae & milk line in mammals? (both involve fluid flow rather than muscle movement, and woulld explain presence of most male mammals retaining vestigial nipples).


  6. No reason to think so in either case.

  7. If the abdomenal swimmerettes of lobsters are homologs to abdomenal mammae and prolegs, perhaps? See:


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