Foto Diarist

Theritas mavors, a Lycaenid butterfly in the subfamily Lycaeninae at Finca Cantaros, San Vito, Costa Rica. The fly wasn’t a predator of the butterfly, but seemed to study the white tips of the waving tail–potential minuscule insects to a fly’s eyes?

It was my unlucky day; it was my lucky day. An early morning birding foray into our nature reserve was disappointing–nothing was moving or calling out. When I returned to the house my dog ran toward me with her rubber chicken. Would I throw it? Of course! When I went to pick it up, I saw a butterfly around the Hamelia patens “scarlet bush”, a small ornamental tree just 25 feet from our back door. Holy moly! What is that? I immediately started taking pictures of what turned out to be Theritas mavors, and called my husband to do a video of the Lycaenid butterfly. 

As it turns out, after getting help with the ID, I learned that over the years I have taken three photos of Lycaenid butterflies in the subfamily Lycaeninae: two on my own property, and one in Belize. I have much more work to do, as Costa Rica has 248 species in the Lycaeninae. The Lycaenidae Family of butterflies is “cosmopolitan” and enjoys tremendous diversity in tropical regions. About 6000 species have been described worldwide–the second largest family of butterflies (behind Nymphalidae), constituting about 30% of the known butterfly species. Lycaenids are divided into five subfamilies, including Lycaeninae, with 511 Lycaenid species identified thus far in Costa Rica. 

Evenus batesii, subfamily Lycaeninae, forest near Chan Chich, Belize.

In the subfamily Lycaeninae, most species have hindwing veins which project into one or two hairy antenna-like tails, some with black and white rings (“annulations”). Note the legs in both Theritas mavors (top) and Evanus batesii (above) also have black and white annulation. Evanus batesii was named after Henry Walter Bates, the brilliant entomologist and contemporary of Charles Darwin and Alfred Russell Wallace. Bates spent eleven years in Brazil between 1848 and 1859, observing and collecting insects and Lepidoptera. 

Batesian mimicry, as it came to be called after he published his famous paper in 1861*,  could involve something as simple as a praying mantis or a moth mimicking the color and patterns of leaves, or an adaptation as complex as an “edible mimic”  gaining some protection from predators by virtue of its close resemblance to a model species  which is unpalatable or toxic.** Bates observed that “The Leptalides flew in the same parts of the forest, and generally in company with the species they mimic.”

Interestingly, in another form of mimicry, the tails of these Lycaeninae butterflies are used to confuse and distract potential predators. In Theritas mavors, the butterfly controls the vertical tail movement: the tails on each wing wave in contrast to one another, mimicking antennae.  (See the video below.) The butterfly often turns around upon landing, putting its tail uppermost to misdirect the predator from recognizing its true head orientation. This may cause the predator to stealthily approach the butterfly from what is actually the true head end, resulting in early visual detection by the butterfly. A predator may then attack the false antennae rather than the actual head part of the body, allowing the butterfly to escape with only minor wing damage. This mimicry with false antennae provides a distinct evolutionary advantage when the butterfly can escape to live another day and reproduce.

As a Lepidoptera enthusiast, I am always excited when a butterfly appears that I’ve never spotted before. A new arrival is cause for quickening pulse and rapid camera action. It is a matter of working to catch my breath when a stunning creature is posing in front of me. Time becomes irrelevant. Everything else falls away. 

The English nature writer, essayist and journalist Richard Jefferies (1848-1887)–always trying to open himself up fully to the beauty of the universe–said it best:

It is eternity now. I am in the midst of it. It is about me in the sunshine; I am in it, as the butterfly in the light-laden air. Nothing has to come; it is now. Now is eternity; now is the immortal life.***

Lycaeninae sp., Finca Cantaros, San Vito, Costa Rica. No ID possible without seeing ventral wings.

References:

*”Contributions to an Insect Fauna of the Amazon Valley. Lepidoptera: Heliconidae“, Encyclopedia.com: Henry Walter Bates.

** For example, Leptalides in the Pieridae Family mimic several unpalatable species in the Heliconidae Family.

***  See his 1883 autobiographical work, The Story of My Heart.

Video of Theritas mavors butterfly tail action by Harry Hull, filmed at Finca Cantaros, Costa Rica.

Mariposas de Costa Rica; Butterflies and Moths of Costa Rica (Order Lepidoptera) by Isidro Chacon and Jose Montero, Editorial INBio, 2007, Costa Rica, pp. 272-277. (Out of print.)

Wikipedia: Lycaenidae; Lycaeninae.

Wikipedia: Batesian mimicry.

Acknowledgement: Thanks to my friend, Isidro Chacon, for help with identifications.

Note: The Lycaenids are also known commonly as Hairstreaks, Blues, Coppers and Metalmarks.