Ithomiini contains some 370 species, named "clearwing"
because their wings are mostly transparent.
The butterflies live in humid forests from
the southwestern United States to Argentina,
where they seek plants containing pyrrolizidine alkaloids.
The alkaloids give the butterflies a distinctive smell and taste that makes
them unpalatable to predators; human expeditions in areas populated with
Ithomiini detect their presence by smell before sight. The butterflies move
slowly between plants and, when alighted, are nearly invisible. Laboratory
observations of predation have failed uniformly because nothing - monkeys,
birds, spiders - will eat them.
The membrane of the wings is transparent because it lacks the colored scales
that give other lepidopterids their characteristic color and leave dust on the hands when touched. The most famous
and photographed Ithomiinid is the greta oto, also known confusingly as
the glasswing butterfly. This species has a broad
brown tract at the front tip of each wing which is traversed by a white stripe.
Clearwing butterflies are believed to be indicators of biodiversity
because several species typically exist within a small area. Their common habit
of isolating alkaloids for chemical defense defines them as Mullerian mimics,
similar to bees
and wasps which
are close in appearance and share a defense mechanism.
One imagines that European colonists traversing the neotropical forests of South America caught glimpses of them in the shafts of light breaching the
canopies, where superstition might have defined them as indicators of magic.
Today, researchers photographing them on wilted borages recognize their magic as the expression of alleles,
knowing that in the right context the two breeds of superstition are
indistinguishable - Mullerian mimics of one another.
Wikipedia. "Ithomiini." http://en.wikipedia.org/wiki/Ithomiini, 4/15/15.
---. "Butterflies and Moths of North America." http://www.butterfliesandmoths.org/taxonomy?s=103&sci=Ithomiinae&com=Clearwing%20Butterflies, 4/15/15.
insects.org. "Clearwing Butterfly." http://www.insects.org/entophiles/lepi_027.html, 4/15/15.
Rainforest Expeditions. "Clearwing Butterflies." http://blog.perunature.com/2012/09/clearwing-butterflies.html?m=1, 4/15/15.