Animal of the Month
July 2021

Name: Monarch Butterfly

Class: Insecta
Order: Lepidoptera
Family: Nymphalidae
Genus: Danaus
D. plexippus, Monarch Butterfly
D. erippus, Southern Monarch Butterfly
D. cleophile, Jamaican
Number of Subspecies: six, all under D. plexippus

Size: As caterpillars, maximum of 1.9 inches; as butterflies, wingspan of 3-4 inches.
Weight: N/A

Caterpillars long worm-like bodies, tentacles on either end of body, twelve small stubby legs under the body. Butterflies long thin body segmented as head, thorax and abdomen; six thin legs, two long and thin antennae, large brilliantly colored wings.
Color(s): Caterpillars small black, yellow and white stripes. Butterfly wings are orange, amber or sometimes white, veined with thick black lines and lined on the tips with white spots; bodies are black with white spots. Male butterflies have noticeable black spots on the veins in their lower wings, females lack these spots.
Behavior: Herbivorous, some are migratory.
Preferred Habitat: Wherever milkweeds are plentiful, including fields, forests, gardens and agricultural areas.
Range: Across North America from southern Canada to northern South America. Also found in Hawaii, Australia, New Zealand, Indonesia, Papua New Guinea, and multiple islands in the Indian, Pacific, and Atlantic oceans.
Diet: Caterpillars leaves and seeds from milkweed plants. Butterflies nectar from various milkweed plants.
Lifespan: 15 days to 8 months depending on the time of year, about 2-6 weeks in captivity.

Status: D. cleophile Near-Threatened, D. erippus Not Evaluated, D. plexippus G4 Apparently Secure

Have you ever been surprised to learn new things about old friends despite having known them for a long time? You can add the monarch butterfly to that list! The monarch butterfly is one of the most recognized and celebrated butterfly species, yet there is more to this critter than its beautiful wings.

One thing you might not have known about monarch butterflies is that they can be found across half the planet! Monarch butterflies are most famous for their presence in the Americas, ranging from southern Canada to northern South America. But they also have strongholds in Hawaii, Australia, Indonesia, Papua New Guinea, and dozens of islands across the Indian, Pacific and Atlantic Oceans! Most monarch species stay in one region or make small migrations, but the subspecies D. plexippus plexippus is famous for its massive migration across North America. This is the only known insect species that makes a two-way long-distance migration like birds!

Another fact you might not know about monarch butterflies is that they don't all have the same colors. Most monarchs are known for their glorious amber or orange wings, but occasionally a monarch butterfly will display white wings! A white monarch is called a nivosus, and it's thought to occur because of genetic variations. Nivosus monarchs usually don't survive long because they are easier targets for birds, but in Hawaii it has been reported that ten percent of the monarch butterflies are nivosus!

Yet another crazy lesser-known fact about monarch butterflies is that their lifespan varies depending on what time of year they are born. Usually, four generations of monarch butterfly will occur in a single year! The first generation runs from about February through March. These monarchs will lay eggs for the second generation, which hatches in April or May. The second generation will lay third generation eggs, which will hatch in June or July. The third generation will lay fourth generation eggs hatch in August or September. The fourth-generation monarchs live the longest; many migrate during the winter months so they can start the next first generation in February.

So, how long does a monarch butterfly live? The answer is, depending on the time of year, as short as about two weeks or as long as eight months!

Like all butterfly species, monarch butterflies start lives as caterpillars. After eating their own eggshells, they seek out milkweed leaves and seeds to feast on. A caterpillar will go through five "instar" phases, meaning it will molt and shed its skin five times. After the fifth instar, the caterpillar will hang from a stem and encase itself in a green pupa. Several days later, the butterfly will emerge, dry its wings, and take flight! Adult butterflies will seek out the nectar of milkweed plants for food. A butterfly will usually mate several times in its adult life.

The monarch butterfly is classed as G4 by the nonprofit NatureServe, which puts it at about near threatened. The Jamaican monarch butterfly has been classed as near threatened by the IUCN, and the southern monarch butterfly has not yet been evaluated. Monarch butterflies are not an uncommon site, but their numbers are decreasing. Alarmingly, Mexico reports that their monarch populations have dropped 80%, while coastal California reports that their populations have dropped 99%. West of the Rocky Mountains, monarchs have declined 50%, and east of the Rockies they have declined 90%. Other populations are also threatened, and the declines are only increasing.

The main concern for monarch butterflies is habitat loss. Much of their milkweeds have been killed, leaving little for them to eat. Climate change, herbicides and an epidemic of parasites are also problems. Sometimes monarch butterflies will get confused and lay eggs on invasive swallow-wort plants instead of milkweed plants; swallow-wort is poisonous to monarch caterpillars.

While major legislation has yet to be taken in defense of the monarch butterfly, environmental organizations are increasingly calling for the monarch to be added to the Endangered Species List. The butterfly is listed as a species of concern in Ontario and endangered in Nova Scotia, and there are movements to list the species as endangered on the national level in Canada. In 2014, President Barrak Obama founded the Pollinator Health Taskforce, which seeks to protect butterflies and other pollinators in the US. Sanctuaries have been founded in California and Mexico, which has helped to give the monarchs a leg up. Meanwhile, many organizations are working tirelessly to bring attention to this beautiful species. It may take time and a lot of work, but there is every reason to hope that monarchs have more to surprise us with in the future.

To learn more about these gorgeous insects and how to help them, check out these awesome organizations:

Xerces Society for Invertebrate Conservation, Monarch Page-Check out what the Xerces Society is doing for monarch butterflies!

Monarch Butterfly Fund-Dedicated to restoring monarch habitat!

Save Our Monarchs Foundation-Establishing safe habitat corridors for monarchs to thrive!

Want to do more for monarch butterflies? You can help by…

  • avoiding using pesticides in your garden. The chemical glyphosate is a common ingredient in pesticides, and this is toxic to monarchs!
  • planting milkweed species native to your area. The more food they have, the more monarchs will thrive!
  • help to identify and remove invasive swallow-wort plants from your area. This will give monarch caterpillars a fighting chance!
  • writing to your representatives. Tell them how important monarch butterflies are to nature, and that you want to see them take action!


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