Rare day-flying moth spotted

Rare day-flying moth spotted

Dan Janzen has sent us an image he has taken of a Male day-flying moth Xanthocastnia evalthe in the family Castniidae, about 2 inch wingspan.

While exploring the edge of the old-growth rain forest in central Sector A on 20 May 2008, I spotted this male Xanthocastnia evalthe , a very fast-flying day-flying moth in the ancient tropical family Castniidae.  The Costa Rican population of this species has also been called Xanthocastnia evalthe tica but we do not have enough information to know if it should be recognized as a distinct species - Xanthocastnia tica – or simply the Central American portion of a widespread neotropical Xanthocastnia evalthe.

This is the first time I have seen a living specimen of this species of fast-flying moth in 45 years of watching moths (and butterflies) in Costa Rica.  Here he is perched 40 cm above the ground watching alertly for passing females, an occupation sufficiently all-absorbing that it allowed me to approach cautiously for its portrait.  Note his butterfly-like antennae and bright colors – a very visually-orienting animal, in contrast to most moths, animals that depend largely on air-born chemicals (pheromones) rather than their appearance for communication among the sexes.  I can only infer its larval food plant species and place from what we know of other species of Castniidae – the larva is probably a stem borer in one of the many species of large-leafed banana plant-like rain forest understory monocots (Heliconiaceae or Marantaceae) in Sector A.  While some of its potential larval food plant species survive as fragmented populations in the agricultural countryside bordering Sector A, it is likely that this moth’s population today survives only in relatively intact forest.

The name of the moth was kindly provided from the photograph (thanks to digital cameras and email we did not have to kill it to learn its name) by Bernardo Espinoza, a curator of Lepidoptera at INBio, Costa Rica’s Instituto Nacional de Biodiversidad, by comparing with their magnificent collections of Costa Rican insects developed over the past two decades by teams of Costa Rican parataxonomists and international taxonomists.

The Sector A work is currently looking for funding to extend the forest North and protect this area of rainforest for ever.

CTF is running a campaign to raise funds for the GDFCF work. We plan to raise £50,000 to help purchase this incredibly diverse habitat. The importance of this habitat is underlined by Dans comment on the picture he sent to us.

I attach an image of a day-flying large moth that I took in May on a property 14a in Sector A. It is Xanthocastnia evalthe (Castniidae) and this is the first one I have ever seen alive.

GDFCF have identified the owners of the land and they have all agreed to sell, we need to raise the funds to get the down payments made. Property 14a that Dan mentions above is 55 hectares and requires approximately $150,000 to purchase. You can see it in the map below.

If you you would like to help, use the donation button at the top of this page.

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rob - who has written 45 posts on Children's Tropical Forests.

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