Note: Although this may not seem to be a relevant post on The Eyrie, I thought it would be a good idea to share the obsession that sparked my passion for the natural world as a whole. I hope this post will inform and excite you about moths; perhaps even making them an obsession of your own!
When you hear of moths, do you cringe at the thought of small, dingy flutterers wreaking havoc on your clothes? Thankfully, for both us and moths, that is not the case. The number of moths we consider to be pests are in a minority. Most moths are very important food sources for migrating birds, they are very important in determining the biological diversity of an area, and are very cryptic in appearance, with amazing patterns. My friend and co-founder of National Moth Week, Liti Haramaty, often likens mothing to birding. Just like people go birding, people go mothing. Just like people keep bird life lists, people keep moth life lists. Just like people attend birding conferences, people attend mothing conferences.
The Luna Moth (Actias luna), a quintessential moth of North American forests. The adults are silk moths in the family Saturniidae, and have no mouthparts, being an evolutionarily more recent family. Found on July 4, 2014, in Freehold, New York. Photo by Jacob Gorneau.
Why are moths attracted to light? Even Shakespeare noted this behavior in The Merchant of Venice, 1596, which has now become a popular idiom: “Thus hath the candle singd the moath.” Although it is not exactly known what causes moths to be attracted to light, many moths see and are attracted to different forms of ultraviolet light. Some scientists think moths use the moon, which, reflects trivial amounts of ultraviolet light that moths may be able to pick up. Another explanation, one which I personally find more sensible, suggests that moths are attracted to the ultraviolet light on the flowers that they pollinate. However, a significant number of moths do not have any mouthparts, but are still attracted to light—perhaps this attraction was retained even though the mouthparts were lost in the evolutionary shuffle?
The ultraviolet light spectrum, courtesy of United Nuclear.
How should I attract moths? While this may seem like a simple question, considering the drove of moths that flood porch lights in the summer, some lights are more efficient than the typical porch light. Visible brightness does not necessarily matter at all—moths see and are attracted to ultraviolet light, and our visible spectrum of light is of little importance to them. Therefore, it is important to focus on the entire light spectrum, while looking for a significant overlap near the ultraviolet light. Mercury vapor lights are often considered the best lights, but they can be fairly expensive. Other less expensive alternatives can perform just as well. I personally use a 20-watt UV blacklight, which is relatively inexpensive in comparison. The light emits only enough visible light for you to tell it is on. If it is in full sunlight the human eye cannot tell if it is on or off. However, one must be careful when buying blacklights, as some are white bulbs coated in a dark purple color to mimic the color emitted by actual ultraviolet blacklights. In addition, I recommend hanging the blacklight or shining it onto a white bedsheet that has been tied between two trees. My setup is pictured below. You can see that I have another white light in addition, but I just use this light to better see the species of moths on the sheet, and not to attract the moths.
My moth setup: a night and day comparison. Photos by Jacob Gorneau.
Estimates of the number of species of moths vary greatly. There are about 160,000 recorded species of moths, over nine times that of butterflies! However, there could be thousands left to be discovered.
From left to right: False Underwing Moth (Allotria elonympha) showing a filiform antenna, seen on June 27, 2014 in Brookside Haven, OH; Polyphemus Moth (Antheraea polyphemus), seen on July 19, 2009 in Freehold, New York, showing plumose antennae; and Monarch Butterfly (Danaus plexippus), seen on August 30, 2011 in Freehold, New York, showing a capitate antenna. Photos by Jacob Gorneau.
What is the difference between a moth and a butterfly? While there is no scientific difference between the two, butterflies tend to have capitate (also known as “clubbed”) antennae, while moths generally have filiform (slender, or thread-like) or plumose (sometimes called “bipectinate” or “feathery”) antennae. Moths can have a frenulum, which is a structure that hooks the hindwing to the forewing, while butterflies generally do not. Moths generally fly at night, while butterflies usually fly by day. However, there are always exceptions to this rule. Moths in the family Castniidae have capitate antennae, and in Australia, there is a skipper butterfly, Euschemon rafflesia, which has a frenulum. In addition, many moths are active during the day.
A male Confused Eusarca (Eusarca confusaria), showing some very plumose antennae. Found at the Huyck Preserve and Biological Research Station in Rensselaerville, New York on July 19, 2014. Photo by Jacob Gorneau.
What is the difference between male and female moths? This is why males generally have plumose antennae—the structure of the antennae allows the moth to pick up the scent of the pheromone. Despite this, females can also have plumose antennae, in which case the males tend to have larger antennae. More often than not, it is nearly impossible to sex moths from a photo, and usually size recordings and genitalia dissections are necessary. In other cases, sexual dichromatism is present, as seen in the Io Moth below (that is, males and females have different colors).
A male and female Io Moth (Automeris io). The male is pictured on the left and has bright yellow forewings, while the female, pictured on the right, has rosy-colored forewings. Male found at Brookside Haven, Glouster, Ohio, on June 27, 2014. Female found at Dock 3, Burr Oak State Park, Glouster, Ohio, on June 28, 2014. Photos by Jacob Gorneau.
How do moths attract mates? Many use pheromones, species-specific chemical compounds, to attract mates. The pheromones are typically picked up by a male’s antennae. In most moth families, females release pheromones to attract males. However, the very primitive Hepialidae family is the reverse, with males releasing pheromones to attract females. In addition, females in this family do not lay their eggs on certain plants while resting, but fly over large areas, dropping their eggs from overhead. Moths in this family are also rarely attracted to ultraviolet light, making them uncommon to rare finds. I was fortunate enough to find one last summer next to our pond, which has a lot of sensitive fern (Onoclea sensibilis), one of the moth’s hostplants.
The elusive Gold-spotted Ghost Moth (Sthenopis auratus), found in Freehold, New York on July 4, 2014. Photo by Jacob Gorneau.
Have you ever touched a moth or butterfly and wonder what the “pixie dust” on your finger is? They are very small scales that cover a moth. The scales have several functions, but most importantly assist in the camouflage of the moth. Moths in the family Sphingidae have stiff scales near their genitals which rub together, producing ultrasound clicks in response to bat echolocation. In fact, butterflies and moths are collectively recognized by the order Lepidoptera. Lepidoptera is from the Greek “lepis,” meaning “scale,” and “pteron,” meaning “wing.”
Green Leuconycta (Leuconycta diphteroides), showing the scales covering the moth. Seen on June 28, 2012 in Freehold, New York. Photo by Jacob Gorneau.
While other people may spend the lazy summer days relaxing, I bird by day and moth by night. Will you join the dark side?
Bibliography
- “Antennae Types.” University of Sydney School of Biological Sciences. Web. Retrieved 29 December 2014. http://bugs.bio.usyd.edu.au/learning/resources/Entomology/externalMorphology/antennaTypes.html
- Britton, Dr. David. “What are the differences between butterflies and moths?” Australian Museum. 20 July 2011. Web. Retrieved 29 December 2014. http://australianmuseum.net.au/What-are-the-differences-between-butterflies-and-moths
- Carver, J. H., Horton, B. H., O’Brien, R. S., & O’Connor, G. G. “The Ultraviolet Reflectivity of the Moon.” The Moon. Volume 9. Issue 3-4. Pages 295-303. Web. Retrieved 17 November 2014. http://articles.adsabs.harvard.edu//full/1974Moon….9..295C/0000295.000.html
- “Lepidoptera.” Online Etymology Dictionary. Web. Retrieved 29 Dec. 2014. http://www.etymonline.com/index.php?term=lepidoptera
- “The Meaning and Origin of the Expression: Like a Moth to a Flame.” The Phrase Finder. Web. Retrieved 15 November 2014. http://www.phrases.org.uk/meanings/232050.html
- “Moths.” BugInfo. The Smithsonian Institution. Web. Retrieved 18 November 2014. http://www.si.edu/Encyclopedia_SI/nmnh/buginfo/moths.htm
- Watson, Traci. “Hawkmoths zap bats with sonic blasts from their genitals.” Nature. 3 July 2013. Web. Retrieved 29 December 2014. http://www.nature.com/news/hawkmoths-zap-bats-with-sonic-blasts-from-their-genitals-1.13333
- “UV & Blacklight.” United Nuclear. Web. Retrieved 27 November 2014. https://unitednuclear.com/index.php?main_page=index&cPath=28_43
