Mystic Aquarium

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Size:

Adult monarchs have a wingspan of approximately 9 to 11 cm and their weight ranges from 0.25 to 0.75 grams, with an average of about half a gram, which is about weight of a paperclip! Males are slightly larger than females. 

Range/Distribution:

There are monarch butterflies in Australia, New Zealand, Hawaii, the Caribbean, North America, Mexico and South America. However, only the Australian and North American monarchs exhibit seasonal movements. North American monarchs form two fairly distinct populations, although recent research has shown that there is some movement between the eastern and western populations. The western migratory population breeds in the western United States and Canada, and winters near the California coast. The eastern migratory population breeds in the central and eastern United States and in southern Canada, and winters in central Mexico (in the eastern part of the state of Michoacán and western part of the state of Mexico). The monarchs that spend the winter in the mountains of central Mexico or eucalyptus groves of coastal California are the final generation of a cycle that begins anew each year. Most of the butterflies in this final generation begin their lives as larvae in the northern United States or southern Canada, and then migrate up to thousands of kilometers to specific overwintering sites. After spending several months at these sites, they fly north and east, starting the cycle again.

Appearance:

Monarchs have bright orange wings with black veins, and black edges that contain white spots along the margin. The underside of the wings is duller orange, so that when the wings are folded in rest, the butterflies appear camouflaged as they cluster or rest singly in trees or on other substrates. Males have a black spot on a vein on each hind wing. Females have slightly more brown scales in the orange patches of their wings, and more black scales over the wing veins, making the veins appear wider.

Habitat:

During the summer butterflies can be found around milkweed plants where they lay their eggs or in areas where they can obtain nectar from flowering plants. In winter, the western population clusters on the Eucalyptus groves of California and the oak-pine-oyamel fir forests located in the mountains of central Mexico.

Food:

Larvae eat milkweed leaves and adult monarchs feed on nectar from flowering plants.

Predators:

During the winter black-headed grosbeaks and black-backed orioles prey on adult monarchs. After capturing a butterfly, the bird takes it to another branch and eats it. Because of their thick beak, grosbeaks eat butterflies by biting them roughly, usually removing their abdomen from the rest of the body. Orioles are able to cut through the exoskeleton (skin of the butterflies) with their beak and then empty the contents of the abdomen and throats with their tongues.
There are also five species of mice that feed on butterflies that have fallen to the ground. The most conspicuous of these species is the scansorial black-eared mouse Peromyscus melanotis. The mouse lives on the ground in the colonies and takes advantage of the abundant food source the butterflies provide during winter.
Mortality is especially high for immature monarchs, with approximately 5% to 10% survival rates from egg to the end of the larva stage. For example, fire ants (Solenopsis invicta) kill up to 100% of monarch larvae in some locations in Texas. Tachinid fly parasitoids cause high mortality rates that vary both with location and year. Other important predators of monarch eggs and larvae include spiders, true bugs, ladybug larvae, lacewing larvae, and paper wasps.

Mean Life Expectancy:

During summer, the generations of adult monarchs live around two to six weeks, while those that migrate may live up to eight or nine months and are not reproductively active until the end of the winter in Mexico. The cool conditions at the roost sites in Mexico, the inactivity of the butterflies, and the lower metabolism during diapause contribute to the longer lifespan of the migratory generation.

Mating Behaviors:

Monarchs are unusual among butterflies in that males are able to force females to mate. The male pursues the female in flight and takes her down to the ground where they copulate, remaining attached for many hours. The male transfers a spermatophore to the female, which contains both sperm and a protein-rich material that she is able to digest and use in both her own tissue and that of her offspring.

FAQ

Monarch Butterfly Fund staff member Monica Missrie answers some frequently asked questions about the monarch butterfly.  Be sure to check out the Monarch Butterfly Fund webpage to learn more about their work with butterflies.

Q: How do monarchs eat?

A: “Adult monarch butterflies sip nectar from flowering plants using a sucking tube, that resembles a soda straw, and is called a proboscis.  You can see it coiled under its head when not in use."

Q: Do monarchs live in other parts of the world besides Mexico and the USA?

A: “Yes, monarchs are found in many places throughout the world, but they probably originated in the Americas, and were spread either with the help of humans or on their own to other places. They are found in Australia and New Zealand, and many islands east of these countries (most islands between Australia and Tahiti have monarchs). They are also found in Hawaii, most islands in the Caribbean, and even sometimes in western Europe.”

Q: Why do monarchs hang in trees?

A: "The trees offer the monarchs protection from extreme temperatures, predators, and precipitation (rain and snow)."

Q: How high can a monarch fly?

A: “Monarchs have been reported by glider pilots at 1250 meters (4062 feet - that's about 3/4 of a mile above the earth's surface!). And, commercial and military pilots have seen Monarchs at 3000-4000 meters over midwestern states in September. How do they get this high? They probably take advantage of or columns of warm air (thermals) just as birds do (e.g. hawks, eagles, vultures)."

Q: How fast do individual migrating monarchs fly?

A: "Clearly, the flight speed of such a small organism depends on environmental such as wind speed and direction relative to the heading (direction) of the butterfly. Monarchs are slow fliers relative to other butterflies and moths, flapping their wings only 5-12 times per second. Their flight speeds have been measured at 5 meters per second, 18 km or 12 miles per hour; but, if disturbed, they can fly much faster for short distances.”

Q: Is it true that monarchs can only see one color?

A: “No, butterflies have the broadest visual spectrum of any known animals, and can see more colors that you can! They can see UV light, which humans can't.”

Q: Do monarchs sleep or do they just rest?

A: "Monarchs are inactive when it's dark, but they can't shut their eyes, because they don't have eyelids. How would you tell if a monarch is sleeping?"

Q: Where do they go and what do they do at night?

A: "They remain still at night, probably on vegetation like bushes and trees, but as far as we know, no one has done a detailed study that involved finding monarchs at night."

Q: Where did the monarch get its name?

A: "Early settlers who came to North America from Europe, particularly those from Holland and England, were impressed by the sight of the Monarch butterfly. So, they named it "Monarch," after King William, Prince of Orange, stateholder of Holland, and later named King of England. The monarchs' color suggested the name."

Q: What is the function of the gold dots on the chrysalis?  Are they really made of gold?

A: "Fred Urquhart first studied the gold spots on monarchs in the 1970s. He felt that the spots were involved in the distribution or formation wing scale coloration. However, the experiments that he did involved cauterizing the gold spots on the pupa, and it is possible that this process may have damaged the underlying tissue and affected the color patterns. Interestingly, all danaine butterflies (monarchs and their relatives) have metallic spots on them. A group of researchers in Germany did a careful study of the properties of these spots. They are not metallic (so they aren't really gold), but the cells reflect light like metals do, giving them the appearance of being metallic. Other danaids have silver, copper, or gold spots. 
Here are some hypotheses for the reasons that these butterflies have metallic-looking spots on their pupae:
a) camouflage they could reflect colors of the surroundings and break up the shape of the pupa; they might also look like dew droplets.
b) Warning coloration
c) Filtering particular wavelengths of light which might be harmful to the monarchs
d) They might not have any function, but just be the result of something else in the cuticle of the insect."

Photos

Videos

Podcast

Species of the Month Podcast: Why do monarch butterflies go on such a long migration?

Join Mystic Aquarium's Kelly Matis and MaryEllen Mateleska as the talk with staff from the Monarch Butterfly Fund to learn more about the fascinating migration of the monarch butterfly.

Download

Kelly and MaryEllen want to hear from you! Send questions, comments and suggestions for future podcast topics to educationinfo@mysticaquarium.org.