Frequently Asked Questions
Compiled by Ernest Williams, James Adams, John Snyder, and others
Here are some Frequently Asked Questions about Lepidoptera, and good answers by experts.
Click on a question to be taken to its answer, or just scroll down the page.
1. What are butterflies and moths?
2. What are the relationships between butterflies and moths?
3. What are the differences among butterflies, skippers, and moths?
4. What is a papilionid, or a noctuid, or a geometrid, or...?
5. How do I find definitions of specialized terms used to describe Lepidoptera and their lives?
6. Why are many butterflies so colorful?
7. Is it true that if their scales are rubbed off of butterflies or moths they can't fly ?
8. What are the biggest and smallest butterflies and moths?
9. How many butterflies and moths are there in the world? In specific parts of the world?
10. How does a caterpillar turn into a moth or butterfly?
11. How long do butterflies or moths live?
12. What are the most common butterflies?
13. What butterflies or moths are the most widespread in the world?
14. Why are scientific names used for butterflies and moths?
15. How do butterflies and moths eat? And do moths eat our clothing?
16. Do Wooly Bear caterpillars predict the next winter's severity by the banding pattern?
17. Is it possible for a butterfly or moth to have both male and female characteristics?
18. Why do moths (and other nocturnal insects) come to light?
19. Are there other sources of information (FAQs) about butterflies and moths?
1. What are butterflies and moths?
Butterflies and moths comprise the order Lepidoptera, one of the major groups of insects. As members of the animal phylum Arthropoda, all insects (the class Insecta) have jointed limbs (arthropoda means "jointed feet") and an exoskeleton. Lepidopterans are characterized by the presence of pigment-bearing scales on their wings, and it is these scales that produce their distinctive colors and patterns. The name Lepidoptera actually means "scaly-winged." When a person touches the wings of a butterfly or moth, some of these scales rub off, producing the "dust" that is spoken of as coming from moths. Other major groups of insects equivalent to the order of butterflies and moths include the beetles (Coleoptera, which means "sheath-winged" for their hard outer wings), flies (Diptera, "two-winged"), and ants, bees, and wasps (Hymenoptera, "membrane-winged"). These four orders of insects are the four which include over 100,000 identified species, and Lepidoptera is second only to the Coleoptera, with some 150,000 identified species (though when most species are described, the Lepidoptera will likely include more than 250,000 species).
2. What's the relationship between butterflies and moths?
Athough butterflies and moths are often thought of as two distinct and equal groupings, the order Lepidoptera is divided by their evolutionary relationships into more than 20 superfamilies (second-level groupings). Just one of these superfamilies includes all true butterflies (Papilionoidea), while a second includes skippers (Hesperoidea), insects that resemble true butterflies. Usually, when people talk about "butterflies," they mean a combination of true butterflies and skippers. The rest of the Lepidoptera, approximately 20 superfamilies, include different kinds of moths. This pattern reflects the great diversity of moths, from spectacular giant silk moths to tiny species that are hard to recognize as scaly-winged insects (Lepidoptera). Most Lepidoptera, therefore, are moths. Butterflies can be thought of as being basically a group of moths specialized to fly during the day.
3. What are the differences among butterflies, skippers, and moths?
Sometimes people think of butterflies as being brightly colored, delicate insects that fly during daylight hours and moths as being heavier-bodied, drab insects that fly at night. While these differences do apply generally, there are many exceptions. Some butterflies are brown with very little patterning, while some moths fly during the day and have bright and distinctive coloration. The most reliable anatomical difference is the shape of the antennae: butterflies have antennae with knobs or swellings at their ends; skippers have hooks or points at the end of antennal knobs; and moths have filamentous (thread-like) or feathery antennae without knobs. Some other characteristics are also reasonably useful for distinguishing butterflies and moths, though for these characteristics there are many exceptions. For instance, when not flying butterflies generally hold their wings spread out to the side or held together vertically (up over the body); skippers hold their wings spread out or with the forewings held at a different angle than the hindwings; and many moths hold their wings mostly flattened or even roof-like over their backs. Less apparent anatomical differences exist among the different groups of Lepidoptera, too.
Butterflies and moths are classified in to different groupings called families. Butterflies or moths that have certain similar characteristics are grouped together in the same family. For instance, most of the largest butterflies in the world, many (but not all) with tail-like projections on the hindwings, are placed together in the Swallowtail family. The scientific name for this family is the Papilionidae. Now, most people would simply refer to a member of this family as a Swallowtail, but you can also refer to them as papilionids or papilionid butterflies. As such, members of the Sulphur and White butterfly family (Pieridae) can also be called pierids; of the Hairstreak, Copper and Blue family (Lycaenidae) as lycaenids, and so on.
Why would anyone choose to use what seems to be a hard name to remember? You will often see these types of names used when referring to moths. Some moth families either have not been given a common name or encompass a wide variety of moths with different common names, so there is no single common name for the family as a whole. Therefore, you may often see the name noctuid or noctuid moth used for members of the moth family Noctuidae, which includes more species than any other family of moths. Even though there is a generally accepted common name for the family Noctuidae (Owlet Moths), many of the moth groups included in the family have their own common names (Underwing Moths, Dagger Moths, Forester Moths, Darts, etc.). The term “noctuid” could be used for any of these. The geometrids (also called geometers = “earth measurers") are the adult moths of the inchworms; sphingids are the Sphinx (or Hawk or Hummingbird Moths); saturniids are the Giant Silkworm Moths; and so on.
So, anytime you see an odd butterfly or moth name that ends in “-id”, it is simply a name that refers to the family that includes the indicated butterfly or moth. And, anytime you see a family name, such as Blastobasidae, then you could call the moth that is a member of that family a . . . that’s right, a blastobasid! Just remove the “-ae” off the end of the family name and you’ve got it.
Click HERE to go to an extensive dictionary of terms that are used to describe butterflies and moths.
6. Why are many butterflies so colorful?
As day-flying insects, butterflies are often brightly colored, as are some day-flying moths, to communicate with each other. Night-flying insects, on the other hand, have drab coloration because bright colors are unimportant at night when they can't be seen. One function of colors is to help an insect find a potential mate; colors advertise the species and sex of an individual. Many species are sexually dimorphic ("two forms") because males and females have recognizably different color patterns. If the sexes are dimorphic, then the male is usually the more brightly colored individual, using his brightness to attract mates (the females). Colors may also communicate distastefulness to predators such as birds; even nocturnal (night active) species may be brightly colored for this reason, as resting individuals may be encountered by predators during the day. Through the process of mimicry, some butterflies escape predators by resembling bad-tasting species. Drab coloration, in contrast, may make an insect cryptic or hidden from predators. Colors can also help a butterfly regulate its own temperature. Alpine species, for example, often have dark scales near the body to maximize heat absorption.
7. Is it true that if you rub (the scales off of) the wings, then the butterfly/moth can’t fly? What if parts of the wings are missing?
It is most definitely NOT true. That doesn’t mean you should go around grabbing butterflies and rubbing all the scales off of the wings! Don’t forget that the scales are what give the wings their color, and, as indicated above, the color is important for mate attraction and predator avoidance. Still, during the lifetime of an adult butterfly/moth, it is natural for the butterfly to experience some “wear and tear." At least a few scales are shed/lost every time the butterfly/moth flies, and loss of scales can be dramatically increased in severe weather occurrences. I have personally seen some butterflies flying around with most of the scales missing from the wings. Loss of scales WILL change the aerodynamics of the wings, however, so dramatic loss of scales will change the flight pattern a bit. For that matter, most butterflies and moths can actually lose parts of the wings and still fly. I’ve seen butterflies where the outer third of all wings is missing, or one complete wing is missing, and they are still flying around. Obviously, however, flying under these circumstances is more strenuous for the butterfly, and its flight pattern may change or slow down dramatically. I’ve been fooled by flying damaged butterflies into thinking they are something completely different because they look so weird when they are flying.
Obviously, the longer the butterfly/moth lives, the more likely it is to experience some scale loss or wing damage; it can also be said that the more scale loss and wing damage the butterfly/moth experiences, the more likely the butterfly is to die soon after the damage. However, they are remarkably resilient little creatures, and can experience an amazing amount of “wear and tear” and still be able to fly.
The biggest butterfly is the Queen Alexandra Birdwing (Troides alexandrae), found in New Guinea. Females are known up to 11 inches (280 mm) in wingspan, with a very large wing area, and 12 grams in weight. The African Giant Swallowtail, Papilio antimachus, with incredibly long wings, may exceed the Queen Alexandra Birdwing in wingspan, though not in wing area. The smallest butterflies are various members of the Blue and Hairstreak family (Lycaenidae). The Dwarf Blue (Brephidium barberae) from South Africa, the Pigmy Blues (Brephidium exilis and Brephidium isophthalma) from southern North America, and some members of the mainly neotropical Hairstreak genus Ministrymon all have wingspans around one half inch (12 mm).
The largest butterflies in North America, with wingspans up to 6+ inches (150+ mm), are the Giant Swallowtail of the southern U.S. (Papilio cresphontes), the Tiger Swallowtail (Papilio glaucus), of which the largest individuals are found in Florida, and the western Two-Tailed Tiger Swallowtail (Papilio multicaudatus). The smallest in North America, with total wingspan around 0.5 inch (13 mm), are the Pygmy Blues (Brephidium exilis and Brephidium isophthalma) of the southern U.S.
The largest moths in the world include the following three, all of which may have wingspans greater than 11 inches (279 mm): the Hercules moth (Coscinoscera hercules) of New Guinea and Australia; the Great Owlet Moth or Great Grey Witch (Thysania agrippina), which ranges from the southern tip of Texas into South America and can have a total wing area of well over 100 square inches (645 square cm); and the Atlas moth (Attacus atlas) of southeast Asia, also with a huge wing area. The Madagascan Moon Moth (Argema mittrei) has enormously long tails on its hindwings.
The largest moths in most of the United States are the Polyphemus Moth (Antheraea polyphemus), Cecropia Moth (Hyalophora cecropia), Imperial Moth (Eacles imperialis), Royal Walnut (or Regal) Moth (Citheronia regalis), and Black Witch (Ascalapha odorata), all of which can have 6+-inch (150+ mm) wingspans (typically, it is the females of these species that are the largest; certainly females are heavier because they carry the eggs). The smallest moths have wingspans of only a few millimeters.
9. How many butterflies and moths are there in the world? In specific parts of the world?
Worldwide, around 150,000 species of Lepidoptera have been described, making this order the second richest group of insects (only beetles are more species-rich). Of this number, just under 20,000 are butterflies, which means the other 130,000+ are moths. The actual number of Lepidoptera in the world is considerably larger (estimates run anywhere from 250,000 to 400,000), as there are many species which have yet to be described, particularly in the tropical regions of the world. Even in Europe and the United States, where the fauna is considered to be pretty well known, there are still many new species of moths (and even a few butterflies) that are described each year. Many of these are quite small and dull, but even large and colorful species remain to be (and are) described each year, particularly in the tropics. The tropics have many more species (and in some areas fewer researchers), not to mention that many areas are very little explored, so it should not be a surprise that there are MANY undiscovered species of moths, and even butterflies out there!
As for different regions of the world, the following is a very general estimate of the total number of known (described) butterflies and moths.
Regions of the world:
Nearctic = Canada, United States, and parts of northern Mexico
Neotropical = most of Mexico, Central and South America
Palearctic = mainly Europe and temperate regions of Asia
Ethiopian = mainly Africa and parts of the Middle East
Oriental = mainly warm temperate and tropical regions of southeastern Asia
Australian + Oceania = Australia, New Zealand, Tasmania, and the Islands of the southwestern Pacific/southeastern Indian Oceans (includes Papua New Guinea, Indonesia, etc.)
Butterflies (and skippers) Moths Totals
Nearctic 775 10,850 11,625
Neotropical 7700 37,000 44,700
Palearctic 1575 20,550 22,125
Ethiopian 3650 17,200 20,850
Oriental 4800* 23,500 28,300
Australian/Oceania * 18,500 18,500
Totals 18,500 127,600 146,100
*the total butterflies listed for the oriental region represents the number of species for the Oriental and Australian/Oceania regions combined
Notice that the ratio of known moth species to known butterfly species is about 8 to 1, or, in other words, for every butterfly there are about eight moths. However, if you look at the ratios of moths to butterflies in areas where the moths have been more completely studied (Nearctic and Palearctic) the ratio is higher than 10 moths for every known butterfly. The ratio of moths to butterflies worldwide is likely going to end up being more than 10 moths for every butterfly, once the tropical regions have been more thoroughly studied (assuming we get a chance before the tropical areas are majorly altered by human development!)
The amazing set of transitions that Lepidoptera (and many other insects) undergo during their life cycle is called metamorphosis. Butterflies and moths are among the insects that go through four distinct phases of life: the fertilized egg and embryo, the caterpillar, the pupa (sometimes within a cocoon), and the adult. The transition that most captures our attention is actually two changes: from caterpillar to pupa and then from pupa to adult.
After hatching from the egg, the caterpillar, of course, starts eating. Like any insect, the “skeleton” (exoskeleton or cuticle) is on the outside, so to grow the caterpillar must molt or shed its “skin” several times. Every time it sheds, the caterpillar will “suck in air” to enlarge the new soft cuticle before it hardens. The caterpillar, in other words, must pass through several instars, or different size stages, before it reaches the pupal stage. Also like any insect, the caterpillar has several segments. The segments are covered by a pretty tough cuticle, but between the segments are grooves (called intersegmental grooves) with much thinner cuticle that allow the caterpillar to move, as well as get a little bigger (stretch out). As the caterpillar feeds, the inside of the body “fills up.” So, the cuticle allows only so much growth before the cuticle must be shed.
During caterpillar life, the animal’s brain continuously produces and releases relatively constant quantities of a hormone called Juvenile Hormone (JH), whose function, as the name suggests, is to keep the caterpillar in the caterpillar stage (the caterpillar is, after all, a juvenile!). Each time the caterpillar “gets full,” however, it needs to shed. The intersegmental grooves getting stretched triggers release of a second hormone, Ecdysone, from a gland called the prothoracic gland, which stimulates shedding (ecdysis). The caterpillar then enlarges (as described above) so that it can feed for a while before it has to shed again. So, at each molt there is a burst of ecdysone production, followed by another instar where the caterpillar can feed until it needs to molt again.
During this time, the caterpillar continues producing juvenile hormone. So, with each molt, at least for a while, the caterpillar molts into . . . another caterpillar. When it comes time for this caterpillar to molt into the pupal stage, the level of JH appears to drop appreciably just before the molt, which means the caterpillar will not stay a caterpillar after this molt. End result? This molt leads to a pupa, after which the caterpillar begins producing chemicals that accumulate on the body surface and harden into the tough pupal surface cuticle. (Of course, some moths precede this by busily making and releasing a silk material that becomes a protective cocoon).
Although the pupa may seem to be very quiet (except for occasional twitches and contortions), this is quite misleading. Inside, a radical transformation is occurring. Very early in the caterpillar’s life, several clumps of cells have been set aside in various parts of the body. These clumps are called imaginal discs (appropriately named: another word for adult is imago). Each disc, or pair of discs, is composed of the cells that are the ancestors of adult structures—two eye discs, two wing discs, six leg discs, etc. These discs have no function in the caterpillar, but become very active when the animal becomes a pupa.
During pupal life, nearly all other cells die and their contents are recycled to build a rapidly increasing number of cells in each imaginal disc. Then, each disc unfolds and turns inside-out, revealing the adult shape of a wing or leg or eye, etc. These emerging regions get organized into the adult shape, including a cuticle, all still hidden under the pupal cuticle. (Some internal body parts, such as the nervous system, are retained and re-formed from those of the caterpillar.)
What triggers the emergence (eclosion) of the adult from the pupal cuticle? It can be triggered by some environmental cue, such as warmth (important for a species over-wintering as a pupa), day length (light), or rainfall (important for pupae in a desert environment – rainfall indicates likely availability of larval foodplants). In some cases, emergence may be genetically programmed after a set time period. Whatever the initial trigger, it then sets off a hormonal signal inside the body. This time, a burst of Ecdysone occurs in the absence of JH. This causes the pupal cuticle to split open and also triggers the muscular activities that allow the adult to emerge. For a period after emergence, the adult is quite vulnerable to predators: it must sit quietly and pump fluid into its wings to expand them into their final functional form.
This question often means "how long can an ADULT butterfly or moth live." The question of how long a butterfly or moth can live during its entire life cycle (from egg through to adult) has a different answer.
Some of the longest living adult butterflies include the migrating fall generation of the Monarch Butterfly (Danaus plexippus). They may emerge in August (or even July) of one year, migrate from the United States or Canada to the mountains of middle Mexico, spend the winter there, and then fly down out of the mountains, mate, and lay eggs when it starts to warm up the next year. So the adults can be alive for six to seven months. There are a number of butterflies that "hibernate" over winter as adults, so, basically by default, can survive for several months. The Mourning Cloak/Camberwell Beauty (Nymphalis antiopa) is a classic example of one of the adult hibernators. Species like this may actually be seen flying around during warm days in the winter, even in places like southern Alaska.
Many of the Longwing butterflies of the Neotropics (Heliconius and related genera) may survive for several months, and even roost together and follow a set of regular daily activities. Many, many adult butterflies, however, have a much shorter lifespan (one to two weeks) during which they must reproduce, laying eggs for the next generation.
As for moths, there is not a lot of information that indicates which species are the longest lived as adults. Some of the Sphinx Moths (also called Hummingbird or Hawk Moths, family Sphingidae), probably can live for at least two or three months. Certainly, the fact that some species in this family are found from time to time far out of their normal ranges suggests that they have to be able to survive for quite some time in order to fly long distances. Interestingly, the Giant Silkworm Moth family (the Saturniidae), which contains most of the largest moths in the world and on each continent, do not have long lifespans -- few species can live into a second week after emergence. The reason? Adults have no functional mouthparts! The adults subsist on stored nutrients from the larval stages. So, as adults, their one and only drive is to find a mate, mate and lay the next generation of eggs. Some moths have a much shorter lifespan than the Saturniids. Yucca moths (genus Tegeticula) live for no more than two days (!) as adults, so therefore males and females must have a mechanism for emerging practically on the same day (so they can successfully reproduce).
However, when it comes to longevity, it is NOT the adults that hold any of the records. Most species over-winter as eggs, larvae or pupae, so whichever stage is the over-wintering stage is often the longest part of the life cycle.
There are some more extreme examples of long life in the larval stages. For a lot of species that live in subarctic/arctic/alpine habitats, where the growing season for the larval foodplants is extremely short, the larvae will live for the better part of two growing seasons (more than a year). Eggs that are laid in the fall of one year hatch the next, and the larvae that hatch from these eggs partially develop the first year, diapause (“hibernate”) that first winter, and complete development, pupate, and emerge as adults the next. The end result is that you will encounter adults of these species only every other year.
The champions of longevity, however, have to be the pupal (cocoon/chrysalis) stages of certain species living in specialized habitats. For many species that live in near desert conditions, successful reproduction depends on the adults emerging from the pupa when they can be assured of abundant foodplants for the larvae. This may not happen every year in the desert, however. Emerging from the pupa in a dry year could spell doom for all of the eggs laid by an individual butterfly or moth emerging that year. So, pupae of some species that live in these habitats are able to detect early/abundant rainfall and emerge only in that year, after several years in the pupal stages. I know of one brood of a species (Anisota oslari) that was reared in 1999 having adult individuals emerge in 1999, 2000, 2001, and 2002. Remaining in the pupal stages for several years may not only be possible for these species but a regular occurrence. This seems to be a more frequent occurrence in some of the larger species, like the Giant Silkworm Moths (Saturniidae) and the Swallowtail Butterflies (Papilionidae); this would make some sense as the larger species undoubtedly can pack more nutrients into a larger pupa which would allow longer survival in this stage.
So, when all stages are included, the longest lifespan for certain butterflies and moths will be several years (with most of the time spent in the pupal stages). The absolute shortest life cycles (from egg to adult), are probably around a month (maybe a little shorter), which would mean, of course, that for species like this, they could have several generations in one year.
That depends on which part of the world you are asking about. Some species are extremely localized in their range, while others can cover entire continents or more. Much time and energy has been spent determining the range of each species, and much library/web work must be done to see the results of that research. The next question is related to this topic.
13. What butterflies or moths are the most widespread? In other words, which species are found over the greatest area in the world?
Many butterflies and moths are found in very small areas in very specific habitats. Very few are found over large areas of the world, though there are some that are found on many continents, especially some of the pest species. The one factor that is most important in allowing species to be distributed over a large area is the ability of the larvae to either eat a wide variety of foodplants or some foodplant that is incredibly widespread as well.
Perhaps the most widespread butterfly in the world is the Painted Lady or Thistle Butterfly (Vanessa cardui), which occurs throughout much of the world (except parts of South America). This species is also called The Cosmopolitan, because it is practically cosmopolitan (found everywhere)! Its range even includes many of the islands of the Pacific (including Hawaii), New Zealand, and the Malagasy Republic (formerly Madagascar). A closely related butterfly, the Red Admiral (Vanessa atalanta), is found in Asia, Europe, North America, and North Africa. It is also found in Guatemala, as well as on the Hawaiian Islands. The Monarch (Danaus plexippus) is found over much of North, Central and South America, and is also now established on Hawaii, many of the Pacific Islands, and even Australia. Occasional misdirected migrant individuals are even found in Great Britain.
There are many other very widespread butterflies, such as the Cabbage or Small White (or Cabbage Butterfly; Pieris rapae), which is found in most of the Palearctic region (Europe and Asia), northern Africa and Australia. It is also found over most of North America, though it was introduced to North America. The Long-Tailed Pea (Bean/Lucerne) Blue (Lampides boeticus) is found over virtually all of the temperate and tropical areas of the Eastern Hemisphere and also Hawaii (it is absent mainly from North and South America). The Mourning Cloak (Nymphalis antiopa), also called the Camberwell Beauty in England/parts of Europe and Asia, is found in almost the entire Northern Hemisphere (North America, Europe and Asia).
As for the moths, the Crimson-speckled Moth (Utetheisa pulchella) is found over almost the entire Eastern Hemisphere (much like Lampides boeticus). Its close relative, the Beautiful Utetheisa or Bella Moth (Utetheisa ornatrix [including bella]) is found over much of North, Central and South America (including the Galapagos Islands), so these two species of Utetheisa have virtually the entire world covered! The White-Lined Sphinx Moth (Hyles lineata; several subspecies) is found over much of the world as well, with populations on every continent (except Antarctica), and is even found on the Hawaiian islands.
A few pest or almost pest species of Noctuid moths are very widespread. The Black Cutworm (Agrotis ipsilon) is established on all continents (except Antarctica) and is also found on Hawaii. The same can be said for the Beet or Lesser Armyworm (Spodoptera exigua). The Variegated Cutworm (Peridroma saucia) is found in Europe, North Africa, parts of the Middle East, West Asia, North America, and into northern Central America. The Armyworm Moth (Mythimna [formerly Pseudaletia] unipuncta) is found throughout the Americas, on the Galapagos and Hawaiian Islands and Europe.
The Noctuid genus Heliothis (or two genera Heliothis and Helicoverpa) includes some pest species with broad distribution as well. Similar to the two members of the Tiger Moth genus Utetheisa mentioned above, three species have the whole world covered, one in the eastern hemisphere and two in the western. The Old World Budworm Moth (H. armigera) is found throughout most of Europe, Africa, Asia and Australia, and the Corn Earworm Moth (H. zea) and the Tobacco Budworm Moth (H. virescens) are found throughout the Americas (even Hawaii for H. zea).
One other Noctuid species, The Herald or European Fruit-Piercing Moth (Scoliopteryx libatrix), has a distribution similar to the Mourning Cloak -- it is found over most of the Northern Hemisphere (including northern Africa and Japan). It over-winters as an adult, and is known to be a cave-dweller during the winter. The famous Salt-and-Pepper or Peppered Geometrid (inchworm) moth (Biston betularia) is also found over much of the northern hemisphere, including Japan. It is famous because of the natural selection studies done on the light and dark forms of the moths during the mid-1800's in England, that showed that the dark forms became more common near towns during the Industrial Revolution. Why? Soot covered/killed lichens growing on the trees, lichens against which the light-forms were well camouflaged. Hence, the light forms were no longer camouflaged and fell prey to bird predation, making the dark forms more prevalent. With better pollution controls in place today, light forms have become more common again.
Some smaller pest species are also found virtually worldwide. Two such exampes are the Indian Meal Moth (Plodia interpunctella; pest on a huge range of stored food products) and the Diamond-Back Moth (Plutella xylostella; pest of cabbages and related [Cruciferaceous] foods).
One might think that scientific names (such as Plodia interpunctella and Plutella xylostella) as seen in the answer to Question 13, above), are used just to confuse non-scientists or to appear more “important.” Actually, they are used for the opposite purpose: to provide more clarity and information than common names can provide. At least two functions are performed by scientific naming.
First, it provides clues about which species are closely related. Consider this, for instance. Two North American butterflies are commonly called the Question Mark and the Satyr Anglewing. These names, while colorful and easy to remember, do not provide the clue that the butterflies are closely related and share many features. However, their scientific names tell one that they are in the same genus: the former is Polygonia interrogationis and the latter is Polygonia satyrus. They are different species (that is, they cannot ordinarily mate successfully), but they are (along with other species) similar enough to be in the same genus, Polygonia. Common names can also mislead one in the opposite direction: that two animals are closely related when they are not. As an example, consider the North American butterfly commonly called the Great Spangled Fritillary and the European butterfly with the English name Duke of Burgundy Fritillary. It would seem that they share many features since both are called fritillaries. However, the scientific name of the Great Spangled Frittillary (Speyeria cybele) indicates that it is not so closely related to the Duke of Burgundy Fritillary (Hamearis lucina) since they are not in the same genus. Indeed, they are not even in the same family.
A second very useful function of scientific naming is that it avoids the confusion of two or more common names being applied to the same animal. Consider the butterfly whose scientific name is Nymphalis antiopa. As described in Question 10, it is a widely distributed animal, found throughout the Northern Hemisphere. In England it is the Camberwell Beauty, in Germany it is the Trauermantel, and in North America it is the Mourning Cloak. Even within a single locality, people might have different common names for the same butterfly or moth. For animals, scientific names are decided by a single internationally recognized organization, one of whose jobs is to ensure that no two organisms are given the same pair of names (genus and species). Since the study of science goes across governmental and language boundaries, the use of unambiguous scientific names greatly lowers the level of confusion in books, articles, and meetings.
It should be pointed out that even well-recognized scientific names must sometimes be altered when new information becomes available. For instance, several Tiger Moths that were once placed in genus Apantesis are now in genus Grammia. Why? Because experts on these Arctiid moths examined them and found that they were sufficiently different from Apantesis species to be placed in a separate genus. One hopes that each such change in scientific name reflects a better understanding of “who’s related to whom” than the original name implied.
Moths typically have tube-like mouthparts for sucking nectar or sap or some other liquid. So, no ADULT moth has any interest in eating any part of your clothes.Adult moths are incapable of chewing holes in clothes. It is the larvae (caterpillars) of certain species that eat holes in clothes.
Of the thousands upon thousands of species of moths in the world, there are very few whose larvae will consume fibers in clothing. All of these species are quite small as adults (less than a centimeter long when at rest) – none of the moths that come to your light outside your house are likely to be Clothes Moths. They are also relatively non-descript, not particularly colorful and sitting with wings tightly closed over the body so they have a very thin appearance. Three species are found in North America: they are the Webbing Clothes Moth (Tineola bisselliella), the Casemaking Clothes Moth (Tinea pellionella), and the Carpet or Tapestry Moth (Trichophaga tapetzella), all in the moth family Tineidae. The caterpillars of these moths eat a variety of fibers, including wool, fur, hair, and sometimes linen, silk, and cotton; additionally they may also eat leather, lint, dust, paper, and occasionally even certain synthetic fibers.
For more information, check out the online Ohio State University Extension Fact Sheet, on “Clothes Moths.”
16. I've heard that you can predict how cold the winter will be by looking at how thick the black bands are on a Woolly Bear caterpillar. Any truth in that?
No. The Woolly Bear in question, by the way, is the caterpillar of a Tiger Moth called the Isabella Tiger Moth (Pyrrharctia isabella), an orange-pinkish medium sized adult moth. The hairy caterpillar is typically black on both ends with a broad orangish band in the middle. The tale is that the broader the black bands are on the ends, the harsher the winter. However, the width of black and orange bands is incredibly variable from one individual to the next, and I’ve seen some which are almost completely orange. So, these caterpillars have no ability to predict the harshness of the coming winter.
Although rare, this can happen. The result, in some cases, is an animal that has male characteristics on one side (left or right) and female characteristics on the other side. If the wing patterns are different for the sexes, this leads to an animal rather striking in appearance. A butterfly or moth exhibiting this is called a 'gynandromorph.' For much more detail on how this happens, including some photos, click HERE.
In studies done on the sensitivity of moth optical neurons to light, they are found to have an extremely low threshold, meaning that even very low levels of light will allow the moths to "see." Not necessarily see sharply, but undoubtedly enough to avoid large (dark) objects. All organisms need to be able to orient themselves/navigate within their environment in relation to other objects (foodplants, mates, finding shelter, etc.).
Finding foodplants and mates for moths flying at night is probably done mostly using chemical cues. However, when just "cruising" moths need cues that will allow them to maintain appropriate orientation to surrounding objects, the ground, etc., and one of the cues that is consistent for moths is that light sources (back before the advent of human-made light sources) were predictably"UP" (in the sky). The moon is not always at a consistent angle upward in the sky, but it is always up, as are the stars.
And, by the way, some moths do migrate, needing some cues to direct them. Some noctuid moths migrate using the moon as a primary reference point. To calibrate the location in the sky with actual geographical direction, they periodically use an internal geomagnetic compass. In fact, every hour, they alter their flight path by 16 degrees to correct for travel of the moon across the sky (for purists, rotation of the earth). On moonless nights they navigate solely by the geomagnetic compass. I guess using the moon is 'easier', and therefore they 'prefer' that when it is visible; hence the screwup when artificial bright lights are visible.
The observation that moths appear to (see below) fly more strongly on humid, cloudy nights is also well documented, but to say that it doesn't make much sense therefore that they would use lights as a navigational cue doesn't follow. Most animals have more than one way to navigate through their environment, and just because they don't necessarily use one all the time doesn't mean they can't. (Moths do have functional eyes, after all!) The point? Moths undoubtedly can use lights as a navigational cue, and along with gravitational cues, use the light sources from above to maintain appropriate "up-down" orientation in their environment.
So, why do moths come to artificial lights? The use of moon and stars as navigational cues can at least partly explain why moths end up at lights. Since at least some moths attempt to maintain a certain angle between themselves and natural light sources, this would explain the phenomenon of "spiralling in" that is easily observable in many species as they come to artificial lights.
The reason why they stay at the lights after hitting the "moon," an accomplishment they never evolved a decent response to, is likely to be as follows. Now close to the bright light source, the artificial "moon" has become the "sun", and the moths settle down . . . for their daytime "sleep."
Using night-time celestial light sources as navigational cues would also be a convenient explanation as to why it appears that fewer moths come to lights on well moonlit nights. Full moonlight overwhelms the typical artificial electric light sources. On a cloudy night, it therefore may appear that there is more activity at artificial light sources, though cloudy nights also tend to be warmer and more humid, which may have more of an effect.
However, this is certainly not the entire story. Many, many moths, if you watch them come to light, fly directly at the light source as they come in, with little indication of any spiral. There is a likely explanation for this as well. If you rear butterflies or moths indoors and the adults escape from confinement, they fly straight to the window, or if no windows, or at night, they go straight to the ceiling lights. To me this means that Lepidoptera use light not only for navigation but as an escape route from confined spaces, or possibly darting though an opening in the forest canopy in escape, or may go into the same escape mode when startled or confused. Certainly, at night, in a dark wooded area, the lightest points in the visual background would be those passageways through the branches open to the night sky, and therefore indicating a clear flight path. This probably explains why when at night you walk through surrounding vegetation and stir things up the moths head straight for the light, as does the occasional butterfly. So it is likely that both navigation and an escape reaction are at work in bringing moths to lights.
One last little tidbit. Some have said that moths might hear vibrations from an artificial light source and come to the light based on perceiving that sound. This might be a possibility, but there are three things that suggest this is not a likely mechanism. First, it is incredibly unlikely that white light bulbs and white light bulbs painted yellow emit significantly different sound impulses, and so this would not explain why moths come in to different colored lights in significantly different numbers. Second, there are some families of moths that, in essence, have no hearing capabilities whatsoever (for instance, the Saturniidae [e.g. Polyphemus, Cecropia, Io, Imperial, etc.]). So if sound was the reason, saturniids and some other moths would never come to lights, and this is certainly not the case. Lastly, and perhaps most importantly, there would have to be some reason why the sound is meaningful to the moths. Only a small subset of moths actually use any kind of acoustic communication, so for the majority of moths, sounds at night are likely to indicate danger (flee!) as opposed to some sort of attraction.
Indeed, there are. To find some on the Web, do a search on FAQ and butterflies. And, of course, don't neglect to visit your local library.