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Monarch Facts
In addition to being beautiful, monarch butterflies have an amazing
life cycle. Many people—students, naturalists, scientists and others—have made
it their life’s work to learn more about this incredible insect!
- In the entire world, no butterflies migrate like the monarchs of
eastern North America. Individuals travel much farther than all other tropical
butterflies, up to 2,000 miles.
- Monarch females can lay several hundred eggs, usually laying a single
egg on a plant. The eggs hatch about four days after they are laid.
- Monarch caterpillars eat plants only in the milkweed family. There
are over 100 known species of milkweeds in North America. Monarchs have been reported to feed on 27 of them, but they undoubtedly feed on others as well.
- Adult monarchs drink nectar from many species of flowers. Nectar
contains sugar, which serves as the main energy source for monarchs.
- Monarchs have an effective chemical defense to protect them from
predation; when they eat milkweed, they sequester the poisonous cardiac glycosides in the
milkweed. Cardiac glycosides are poisonous to vertebrates; as a result, most monarchs face
little predation from frogs, lizards, mice, birds and other species with backbones. Their
bright colors also serve as a warning to predators that they contain these poisonous
chemicals.
- Several species of birds—most particularly black-headed
grosbeaks and black-backed orioles—can eat adult monarch butterflies in the
overwintering colonies. While grosbeaks are relatively insensitive to the cardiac
glycosides, the orioles have figured out which parts of the monarch bodies are safe to eat
and avoid the most poisonous parts. Grosbeaks and orioles can kill more than 10% of the
total monarch populations in a winter.
- The monarch caterpillar stage is also known as the larval stage; the
caterpillar is an eating machine, taking few breaks even for resting.
- The monarch larva molts, or sheds its skin, five times before
entering the pupae stage. The entire larval state lasts from 9-14 days under normal summer
temperatures.
- The pupa stage is often called a chrysalis and usually lasts from
8-13 days (the lower time corresponds to warm conditions. It is not a cocoon, since it has
no silken covering.
- Male and female monarchs are easily distinguished: males have a black
spot on a vein on each hind wing that is not present on the female.
- Adult monarchs in summer generations live from 2-5 weeks; those that
emerge in late summer and early fall can live up to 8-9 months to survive the trip to and
from their overwintering sites in Mexico.
- Most monarchs found east of the Rockies winter in the Transverse
Neovolcanic Mountain Belt in Mexico; those found west of the Rockies winter along the
California coast where they roost in Eucalyptus trees, Monterey pines and Monterey
cypresses. California monarchs make up about 5% of the overall worldwide monarch
population.
- In Nahuatl, an indigenous language of Mexico, butterflies are called
'papalotl' . From this word comes the Spanish word for kite: 'papalote'. Monarchs are
known as kites of the mountains.
- Monarch butterflies are found throughout the U.S., in southern
Canada, Caribbean Islands, Australia, New Zealand and other Pacific Islands.
- In 1983, the IUCN Invertebrate Red Data Book designated monarch
migration a threatened phenomenon.
- Not all monarchs migrate. There are continuously-breeding populations
throughout the New World tropics and the Caribbean that remain in the same place
throughout the year.
- When monarchs migrate, they are in a physiological state called
"reproductive diapause," or arrested sexual development. These monarchs will not
mate or lay eggs until their diapause ends in the late winter or early spring.
- Monarchs use "thermals," or updrafts of warm air, to allow
them to glide as they migrate, thus conserving energy for their long flight. Migrating
birds also use thermals.
- Monarchs are in the butterfly family Nymphalidae. Members of this
family appear to have only 4 legs, but they really do have 6; their front pair of legs is
greatly reduced in size and tucked up under their head.
- Mating monarchs remain in copula for up to 16 hours. During that
time, the male transfers nutrients to the female, along with sperm. These nutrients are
used by the female in egg production.
- Spiders, mites, ambush bugs, ants, lacewings, wasps and stinkbugs all
eat monarch eggs or larvae.
- Monarch larvae, like other caterpillars, have very poor vision. They
see through six pairs of simple eyes, called ocelli.
- The long black tentacles on monarch larvae are not antennae. The
antennae are very small and are on the bottom of the larval head.
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