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University
of Rhode Island GreenShare Factsheets
Butterfly
Gardens
Planting
gardens with flowers that attract butterflies is a natural way to
attract these lovely creatures to your yard, garden, patio, or even
window sill. Not only do brightly colored butterflies contribute
aesthetically to any yard, but they are also effective crop and
flower pollinators. Your butterfly garden will also attract birds
and other wildlife. Before you begin your butterfly garden it is
important to know something about butterflies and about their life
cycles, biology and behavior. All
butterflies have the same general life cycle, consisting of four
life stages: egg, larva (the caterpillar), pupa (chrysalis) and
adult (the butterfly). Each stage has special food and environmental
needs. The
cycle begins when butterflies deposit eggs in the spring, summer,
or fall, depending on the species. Butterflies can lay anywhere
from 200 to 1,500 eggs. Some species lay their eggs singly, some
in clusters. A good nectar source is important to the adult's ability
to produce large numbers of eggs. In most cases, eggs hatch within
a few days of being deposited. Caterpillars
emerge from eggs, usually eating the egg shell first, then eating
vegetation, flowers, or fruit of the host plant. Some butterfly
species feed on only one kind of plant and sometimes on only
a certain
part of the plant. Other species may feed on a variety of plants.
The caterpillar or larval stage allows time for growth. Although
a caterpillar looks soft, its skin is actually a skeleton and
is
relatively inelastic. Caterpillars "grow" by molting or shedding
their "skin" several times. Each stage of molting is called an "instar." The
number of instars depends on the species, but is usually four or
five. The rate at which a caterpillar grows increases with each
molt because the larva eats more food as it enlarges. How large
a caterpillar is at its last instar determines the size of the
adult
butterfly. Caterpillars with abundant, high-quality food eat for
less time and become adults more quickly than poorly fed larvae.
Once a caterpillar is full size, it enters the pupal or chrysalis
stage. Using silk produced by silk glands, the caterpillar attaches
itself to a plant (or other object). Some butterflies, such as skippers,
pupate inside a thin covering of silk and leaves. The caterpillar
stays still for about a day as the pupal skin forms under the caterpillar
skin. Then the old skin splits open and the pupa emerges. Pupae
of some kinds of butterflies can be green or brown. The pupae of
monarch butterflies are bright green.
In this pupal phase in the cocoon, the caterpillar undergoes changes
and metamorphoses into a butterfly (adult). The length of the pupal
stage varies with each species and often depends on temperature.
Usually, it takes about two weeks. Some species must go through
a hibernation stage, or diapause, before emerging as an adult. Once
the organs have matured, the skin of the pupa splits and the butterfly
emerges. After a few hours, wherein the wings expand and the skin
hardens, the adult is able to fly, sip nectar, mate, and lay eggs,
thus repeating the life cycle. The entire process-- from egg to
caterpillar to butterfly--takes an average of five to six weeks.
Some kinds of butterflies have only one generation per year. Others
may go through two or three generations in a season. Most butterflies
live for two or three weeks although some, such as the mourning
cloak which spends the winter as an adult, may live for 10 months
or more. The
butterfly's life cycle requires food for both the adult and caterpillar
stages. Certain butterfly species will lay eggs on only one, or
a few, plant species. Other butterflies lay eggs on many plant species.
Generally, butterflies lay eggs only on plants that are appropriate
as a larval food source, although this is not always the case. Tiger
swallowtails feed on tulip poplar, and the mourning cloak on aspens.
Monarch caterpillars feed on milkweed leaves. Milkweed contains
toxins that the larvae can ingest without harm, but which makes
the caterpillars unpalatable to predators. Butterflies may lay their
eggs on or near the kind of plants on which the caterpillars feed.
The caterpillar may prefer the leafy parts of a variety of host
plants, including flowers, vines, shrubs, trees, and weeds. Unlike
caterpillars, adult butterflies feed on a variety of nectar-producing
flowers. Butterflies
appear in spring when the temperature is above 60 degrees F, and
can be observed through late fall. Butterflies are interesting to
watch. You may wish to view them in your butterfly garden and keep
a record of which butterflies visit specific plants. Some of their
interesting behaviors include the following.
Nectaring
Adult butterflies take nectar from many plants. Some plants produce
nectar to attract insects, birds, and other wildlife so the plants
will be pollinated. The nectar is sipped through a long, straw-like
proboscis that is usually kept coiled. The insects' feet have special
taste receptors that can detect sweet liquids, causing the proboscis
to uncoil when it comes in contact with the nectar. Puddling Sometimes a dozen
or more butterflies will gather round a puddle or wet place.
This behavior is called "puddling" during which butterflies
sip nutrients with their proboscis. Animals such as butterflies
that eat only plant nectar need extra minerals and salts to
supplement
their diets. Butterflies most often seen puddling include swallowtails,
fritillaries, and skippers. Basking Butterflies fly best
when their body temperature is between 85 Â100
degrees F. If colder, they need to warm up. They do this by basking
in the sun with their wings outstretched to absorb heat. If
the
temperature goes below 80 degrees F, butterflies can be seen basking
before they begin flying. Roosting
Butterflies need a place to roost during the night, and often pick
the underside of a leaf. If you want to see where they roost, wait
until late afternoon and follow them to their roosting spot. Butterflies
also roost during rainy, cloudy, and cold weather. Usually they
spend about 14 hours each day roosting, usually from sunset until
midmorning. Hibernation
and Migration
According to species, butterflies spend the winter in different
ways and places. Most, however, winter in the same areas where they
spend the summer. The monarch is the only truly migratory butterfly.
They migrate as far south as Mexico, returning to the Northeast
in the spring. It takes several generations of monarchs to make
the trip from North America to their overwintering grounds in Mexico
and California. Monarchs that migrate in the fall have just emerged
from the pupae; monarchs that migrated to our area this spring are
the second or third generation of those that overwintered in the
south. It's still a mystery how these animals know their migratory
route. Mourning
cloaks overwinter as adults in protected places such as loose bark,
log piles, or buildings. At about 60 degrees F they begin to fly
even if the calendar says it is still winter. For that reason, mourning
cloaks are often the first butterflies seen in the spring. They
may have a ragged look because of their long winter. Most blues
overwinter as pupae, and viceroys overwinter as caterpillars. You
can buy or make hibernation boxes to offer butterflies protection
from predators through the winter, but they are not essential if
you provide sufficient food, water, and cover. Only a few kinds
of butterflies hibernate in the Northeast and these are not generally
colonial, so they probably will not use the hibernation boxes. If
you wish to use hibernation boxes, attach them to a tree or post
in a shady place near host plants.
Butterflies require shelter from the elements and a place to roost.
Shrub foliage is useful as a windbreak as are patches of tall grass.
You also can provide a place for butterflies to roost, perch, or
even hibernate by building a log pile and placing the logs crosswise
to create as many open spaces as possible. The ideal log pile size
is 5 feet high and 6 feet long. Log piles, suitable for large yards
or farms, should be in the shade near host plants.
Some butterflies such as the mourning cloak, red admiral, and viceroy
feed primarily on rotting fruit, tree sap, and even manure. For
these butterflies, set out a fermented brew of rotting bananas,
plums, and pears to which you have added stale beer, or sugar, or
molasses and yeast. This mixture attracts butterflies and can be
smeared on tree trunks to simulate sap. You
can make a homemade feeder filled with a solution of sugar water:
4 parts water to 1 part granulated white sugar. Extra solution can
be kept in the refrigerator. You can make a feeder by filling a
dish or flat container with an absorbent material such as tissue
paper and saturating it with sugar solution. This arrangement allows
butterflies to perch while feeding. So the feeder will stand out,
put the feeder near nectar flowers on a post about six inches higher
than the tallest flowers. Butterfly tables can be made by placing
dishes of sugar water and rotting fruit on a table about five feet
off the ground. You may need to lubricate it with a slippery substance,
such as petroleum jelly, to keep ants from climbing up.
It is best to refrain from transplanting larvae to your garden from
other areas because of the risk of introducing harmful exotic species.
A classic example of this is the gypsy moth, a non-native introduced
pest that causes millions of dollars of damage to trees annually.
It is best to work with native species of animals and plants adapted
to your area. Using native plants is encouraged, but digging them
from natural areas such as parks is illegal. You can dig on private
property with permission. The best approach may be to gather seed
from native plants you wish to have in your garden. Many butterflies
tend to live out their lives within a relatively small area.
A few species stay in proximity
and turn into regular
visitors. Lawns that are excessively trimmed, mowed, and covered
with pesticides provide poor environments for butterflies. Therefore,
if you
want to have a flourishing butterfly garden, you need to provide
wildflowers, tall grass, and perhaps some weeds, in a pesticide-free
setting. If you use pesticides to eliminate garden pests, you
also
may harm your butterflies. This includes the use of the bacterial
insecticide Bt (Bacillus thuringienseis) which can kill butterfly
larvae. The
butterfly garden should include a shallow pool or wet area, although
butterflies can get moisture from dew. Butterflies like to perch
on trees and shrubs, so dogwoods, wild cherry, and redbud are good
garden choices. Large rocks strategically placed may serve as a
resting and sunning spots for butterflies. Scent
and color are important to attract butterflies. They have sensors
for smell and taste in various places on their bodies, but most
smell with their antennae or forelegs. Butterflies perceive shapes
only at close range but can see more colors than humans, and they
can see ultraviolet light. Therefore, planting a variety of flowers
is better than planting only one species. The best color combination
is yellow, mauve, or lavender flowers with a strong scent. Purples
and reds are also good colors to select. Remember, if you
want to attract "flying flowers" as butterflies
are called, you need to provide plants attractive to both caterpillars
and butterflies in a natural setting. References:
The Audubon Society Field Guide to North American Butterflies,
Alfred Knoph, 1981
The Butterfly Book, Donald and Lillian Stokes, Little, Brown
and Company, 1991 Handbook
for Butterfly Watchers, Robert Pyle, Houghton Mifflin Co., 1992
How
to Attract Hummingbirds and Butterflies, Ortho Books, 1991 Adapted
from Norma Jean Venable, West Virginia University Extension Service,
2001
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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