Monarch Butterflies Return To Wisconsin
Map of Monarch butterfly spring and
summer migration
Wisconsin is in the core breeding ground for the eastern migratory population of monarchs.
Wisconsin's milkweed feeds and produces several generations of the iconic black and orange
beauties each spring and summer before a final wave gorges itself on wildflower nectar and embarks
on a 1,700-mile journey to central Mexico.
These long-distance fliers, the weight of a paper clip, spend their winter resting in fir trees in the
mountains before migrating north. They get as far as Texas before laying eggs and dying. Their
offspring take up the journey, and it is mostly this generation of butterflies that reaches Wisconsin in
the May and lays their eggs, beginning the cycle again.
Monarchs return in May — milkweed is the only host plant for Monarch butterfly caterpillars.
Midwestern states, including Wisconsin, once provided more than 85 percent of monarch butterflies
in the eastern migratory population. The introduction of herbicide-tolerant corn and soybeans and
the accompanying increase in herbicide use in the 1990s inadvertently led to steep losses as
milkweed disappeared from between rows of corn and soybeans.
Now the new generation of Monarchs will begin their multi-generational migration northward. These
shorter-lived Monarchs have a two to six-week lifespan and travel only part of the way to their
destination. The first generation of the shorter-living Monarchs only make it as far as the southern
U.S. During this leg of the journey, the butterflies lay as many eggs as possible: one adult may lay up
to 100 eggs.
It takes three generations to reach their breeding grounds in the northern U.S. On their journey, they
lay their eggs exclusively on milkweed and then perish. Each subsequent generation continues
north, the cycle repeating until the Monarchs reach their destination.
Monarch Butterfly Fun Facts
The male monarch has two dots near the back of its wings, which distinguish it from a female.
A female that is ready to mate will land next to a male on the ground. If the male is interested, he
will scoop up the female and they will fly together into a tree or other vegetation to mate.
It takes about a month to metamorphose from egg to caterpillar to chrysalis (a caterpillar with a
self-produced veneer type coating) to butterfly.
Three newly hatched caterpillars will fit on a grain of rice, but as they eat milkweed, they grow to
1,000 times their initial size in two weeks.
In fall, monarchs fly from Wisconsin to Mexico, taking about a month to fly up to 1,500 miles. They
spend the winter in the mountain forests of central Mexico, and their children fly north in the spring.
These species are native to the Midwest, easy to grow, versatile in their habitat preferences, attractive,
and have a variety of colors and blooming times. Many of the showiest species on the list are "late
blooming" species, which are especially important for monarchs. Late summer is when they are
fueling up on nectar for their long migration to Mexico. These species will also attract a variety of
other butterflies and pollinators.
Anise Hyssop (Agastache foeniculum)
Crooked-Stem Aster (Symphyotrichum prenanthoides)
Butterflyweed (Asclepias tuberosa)
Common Milkweed (Asclepias syriaca)
Meadow Blazingstar (Liatris ligulistylis)
New England Aster (Symphyotrichum novae-angliae)
Orange Coneflower (Rudbeckia fulgida)
Downy Phlox (Phlox pilosa)
Purple Coneflower (Echinacea purpurea)
Swamp Milkweed (Asclepias incarnata)
Showy Goldenrod (Solidago speciosa)
Black-eyed Susan (Rudbeckia hirta)
Design A Butterfly Garden
Take The Butterfly Quiz
Monarch Life Cycle
WisconsinButterflies.org
Southern Wisconsin Butterfly Assn (NABA)
Monarch Spring Migration
The Eastern migratory monarch butterfly is at risk: new reports show a sharp population
decline and a loss of habitat in the forests where they winter each year. In just one year,
the presence of monarch butterflies in their wintering grounds dropped 22%, from 7 acres
to nearly 5.5. acres.
This is part of a mostly downward trend over the past 25 years—when monarchs once
covered more than 45 acres of forest.
According to
Monarch Watch, "the numbers for Texas are down. That could mean the
population is down, with fewer returnees or it could mean that monarch activity was
low due to cool weather so fewer were seen. The latter seems possible since I've
seen a number of reports by observers that mention the sightings of many monarchs
over time or on single outings. While some of the monarchs arrived ahead of the
emergence of milkweeds in some areas, it appears that the majority of eggs laid by
returning monarch were laid in Texas, where due to slightly warmer temperatures,
the larvae will develop faster than if the eggs were laid further north."
Every year, Eastern monarch butterflies travel up to 2,800 miles from Canada and the
US to their wintering sites in the forests of Mexico. There, in what is known as the Monarch
Butterfly Biosphere Reserve, monarchs cluster in shelter from winds, rain, and low
temperatures.
Monarchs require a vast, healthy migratory path and large, robust forests for survival
through the winter. Today, the butterflies face a reduction of breeding habitat in the US
due to herbicide application and land use changes as well as forest degradation in
wintering sites in Mexico. Extreme weather conditions in all these ecosystems can further
their decline.