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Ordering Information Order your Monarch Watch tags, T-shirts, seeds, posters, videos, live critters and a whole lot more! Multimedia Gallery Monarch photos, drawings, essays and more! Conservation Find out about these issues and how you can help. In the Classroom Lots of great information about using monarchs in the classroom.
Research Projects Here you'll find several ongoing projects that rely on student-scientist partnerships. Reading Room Articles and bibliographies relating to monarchs. The western population overwinters in various coastal sites in central and southern California. The overwintered population of those east of the Rockies may reach as far north as Texas and Oklahoma during the spring migration.
The second, third and fourth generations return to their northern locations in the United States and Canada in the spring. In both caterpillar and butterfly form, monarchs are aposematic —warding off predators with a bright display of contrasting colors to warn potential predators of their undesirable taste and poisonous characteristics. Large larvae are able to avoid wasp predation by dropping from the plant or by jerking their bodies. Aposematism Monarchs are foul tasting and poisonous due to the presence of cardenolide aglycones in their bodies, which the caterpillars ingest as they feed on milkweed.
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Additional studies have shown that different species of milkweed have different effects on growth, virulence, and transmission of parasites. There are two possible explanations for the positive role of A. After the caterpillar becomes a butterfly, the toxins shift to different parts of the body. Since many birds attack the wings of the butterfly, having three times the cardiac glycosides in the wings leaves predators with a very foul taste and may prevent them from ever ingesting the body of the butterfly. Mimicry Monarchs share the defense of noxious taste with the similar-appearing viceroy butterfly in what is perhaps one of the most well-known examples of mimicry.
A growing number of homeowners are establishing butterfly gardens; monarchs can be attracted by cultivating a butterfly garden with specific milkweed species and nectar plants. Efforts are underway to establish these monarch waystations. Sanctuaries and reserves have been created at overwintering locations in Mexico and California to limit habitat destruction.
These sites can generate significant tourism revenue. Organizations and individuals participate in tagging programs. Tagging information is used to study migration patterns. The novel by Barbara Kingsolver , Flight Behavior , deals with the appearance of a large population in the Appalachians. One of the most direct ways humans are interacting with monarchs is by rearing them in captivity, which has become increasingly popular, although there are risks to this activity, and this has become a controversial topic. On the one hand there are many positive aspects of captive rearing.
Monarchs are bred in schools and used for butterfly releases at hospices, memorial events and weddings. Where this practice becomes problematic is when monarchs are "mass-reared". Stories in the Huffington Post in and Discover magazine in have summarized the controversy around this issue.
Some individuals have taken this practice to the extreme, with massive operations that rear thousands of monarchs at once, like one in Linn County, Iowa. This parasite can rapidly build up in captive monarchs, especially if they are housed together. The spores of the parasite also can quickly contaminate all housing equipment, so that all subsequent monarchs reared in the same containers then become infected. One researcher stated that rearing more than monarchs constitutes "mass-rearing" and should not be done.
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In addition to the disease risks, researchers believe these captive-reared monarchs are not as fit as wild ones, owing to the unnatural conditions they are raised in. Homeowners often raise monarchs in plastic or glass containers in their kitchens, basements, porches, etc.
Such conditions would not mimic what the monarchs are used to in the wild, and may result in adult monarchs that are unsuited for the realities of their wild existence. In support of this, a recent study by a citizen scientist found that captive-reared monarchs have a lower migration success rate than wild monarchs do. The monarch was the first butterfly to have its genome sequenced. The genome provides researchers insights into migratory behavior, the circadian clock, juvenile hormone pathways and microRNAs that are differentially expressed between summer and migratory monarchs.
There is no genetic differentiation between the migratory populations of eastern and western North America. There appears to be no genetic difference between a migrating and nonmigrating monarch but the gene is expressed in migrating monarchs but not expressed in nonmigrating monarchs. Fish and Wildlife Service initiated a status review of the monarch butterfly under the Endangered Species Act with a due date for information submission of 3 March The number of monarchs overwintering in Mexico has shown a long-term downward trend.
Since , coverage numbers have been as high as 18 hectares 44 acres during the winter of —, but on average about 6 hectares 15 acres. Coverage declined to its lowest point to date 0. The average population of monarchs in was estimated at million. Historically, on average there are million monarchs. The increase was attributed to favorable breeding conditions in the summer of A study in claimed that the long-term trend in the size of the overwintering sites is cause for concern.
This move, once enacted, would protect critical monarch habitat in Canada, such as major fall accumulation areas in southern Ontario, but it would also have implications for citizen scientists who work with monarchs, and for classroom activities. If the monarch were federally protected in Canada, these activities could be limited, or require federal permits. There is increasing concern related to the ongoing decline of monarchs at their overwintering sites; based on a twenty-year comparison, the overwintering numbers west of the Rocky Mountains have dropped more than 50 percent since and the overwintering numbers east of the Rockies have declined by more than 90 percent since In February , the U.
Fish and Wildlife Service provided a statistic showing that nearly a billion monarchs have vanished from the overwintering sites since At that time, one of the main reasons cited was the herbicides used by farmers and homeowners on milkweed, a plant used as a food source, a home and a nursery by the monarchs. A number of conservationists attribute the disappearance of milkweed species to agricultural practices in the Midwest , where genetically modified seeds are bred to resist herbicides that eliminate milkweed nearby. Growers eliminate milkweed that previously grew between the rows of food crops.
Corn and soybeans are resistant to the effect of the herbicide glyphosate. The increased use of these crop strains is correlated with the decline in monarch populations between and While herbicide-use has been proposed as one factor causing the decline in overwintering numbers of eastern monarchs, it is not the only possibility.
Another is that the monarchs are experiencing problems reaching Mexico. This idea has been embraced by a number of leading monarch researchers, largely because of recent evidence showing that the number of breeding adult monarchs has not declined in the last two decades, based on long-term citizen science data.
One expert has proposed that a large and growing threat to migrating monarchs is mortality from car strikes. Larvae feed exclusively on milkweed and consume protective cardiac glycosides. Toxin levels in Asclepias species vary. Not all monarchs are unpalatable, but exhibit Batesian or automimics. Cardiac glycosides levels are higher in the abdomen and wings. Some predators can differentiate between these parts and consume the most palatable ones.
Several species of birds have acquired methods that allow them to ingest monarchs without experiencing the ill effects associated with the cardiac glycosides. The oriole is able to eat the monarch through an exaptation of its feeding behavior that gives it the ability to identify cardenolides by taste and reject them.
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As a result, orioles and grosbeaks will periodically have high levels of cardenolides in their bodies, and they will be forced to go on periods of reduced monarch consumption. This cycle effectively reduces potential predation of monarchs by 50 percent and indicates that monarch aposematism has a legitimate purpose. Some mice are able to withstand large doses of the toxin. Overwintering adults become less toxic over time making them more vulnerable to predators.
In North America, eggs and first-instar larvae of the monarch are eaten by larvae and adults of the introduced Asian lady beetle Harmonia axyridis. One monarch researcher emphasizes that predation on eggs, larvae or adults is natural, since monarchs are part of the food chain, thus people should not take steps to kill predators of monarchs. On Oahu , a white morph of the monarch has emerged. This is because of the introduction, in and , of two bulbul species, Pycnonotus cafer and Pycnonotus jocosus. They are now the most common insectivore birds, and probably the only ones preying on insects as large as the monarch.
Monarchs in Hawaii are known to have low cardiac glycoside levels, but the birds may also be tolerant of the chemical. The two species hunt the larvae and some pupae from the branches and undersides of leaves in milkweed bushes. The bulbuls also eat resting and ovipositing adults, but rarely flying ones. Because of its color, the white morph has a higher survival rate than the orange one. This is either because of apostatic selection i. Parasites include the tachinid flies Sturmia convergens  and Lespesia archippivora.
Lesperia -parasitized butterfly larvae suspend, but die prior to pupation. The fly's maggot lowers itself to the ground, forms a brown puparium and then emerges as an adult. Monarch chrysalises are parasitized by pteromalid wasps , specifically Pteromalus cassotis. Up to adults emerge from the chrysalis after 14—20 days,  killing the monarch.
The bacterium Micrococcus flacidifex danai also infects larvae. Just before pupation, the larvae migrate to a horizontal surface and die a few hours later, attached only by one pair of prolegs, with the thorax and abdomen hanging limp. The body turns black shortly after. The bacterium Pseudomonas aeruginosa has no invasive powers, but causes secondary infections in weakened insects.
It is a common cause of death in laboratory-reared insects. The protozoan Ophryocystis elektroscirrha is another parasite of the monarch. It infects the subcutaneous tissues and propagates by spores formed during the pupal stage. The spores are found over all of the body of infected butterflies, with the greatest number on the abdomen.
These spores are passed, from female to caterpillar , when spores rub off during egg laying and are then ingested by caterpillars. Severely infected individuals are weak, unable to expand their wings, or unable to eclose, and have shortened lifespans, but parasite levels vary in populations.
This is not the case in laboratory rearing, where after a few generations, all individuals can be infected. This results in overwintering populations with lower parasite loads. The black swallow-wort Cynanchum louiseae and pale swallow-wort Cynanchum rossicum plants are problematic for monarchs in North America. Monarchs lay their eggs on these relatives of native vining milkweed Cynanchum laeve because they produce stimuli similar to milkweed. Once the eggs hatch, the caterpillars are poisoned by the toxicity of this invasive plant from Europe.
The area of forest occupied has been declining and reached its lowest level in two decades in The decline is continuing but is expected to increase during the — season. Mexican environmental authorities continue to monitor illegal logging of the oyamel trees. The oyamel is a major species of evergreen on which the overwintering butterflies spend a significant time during their winter diapause , or suspended development.
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A study acknowledged that while "the protection of overwintering habitat has no doubt gone a long way towards conserving monarchs that breed throughout eastern North America", their research indicates that habitat loss on breeding grounds in the United States is the main cause of both recent and projected population declines.
Climate variations during the fall and summer affect butterfly reproduction. Rainfall, and freezing temperatures affect milkweed growth. Omar Vidal, director general of WWF-Mexico, said "The monarch's lifecycle depends on the climatic conditions in the places where they breed. Eggs, larvae and pupae develop more quickly in milder conditions.
To warm up they will sit in the sun or rapidly shiver their wings to warm themselves. There is concern that climate change will dramatically affect the monarch migration. A study from examined the impact of warming temperatures on the breeding range of the monarch, and showed that in the next 50 years the monarch host plant will expand its range further north into Canada, and that the monarchs will follow this.
There has been a major push to conserve the monarch butterfly, which has been largely fueled by reports of the declining numbers of overwintering monarchs. Meanwhile, numbers of breeding monarchs in eastern North America have not declined. The number of migrating Monarch butterflies sank to the lowest recorded population level in —14, and there is an imminent risk of failed migration.
The strategy lays out current and planned federal actions to achieve three goals, two of which are:. There have been a number of national and local efforts underway to establish pollinator habitat along highways and roadways, although this effort is controversial. Conservationists are lobbying transportation departments and utilities to reduce their use of herbicides and specifically encourage milkweed to grow along roadways and power lines. Reducing roadside mowing and application of herbicides during the butterfly breeding season will encourage milkweed growth.
Conservationists lobby agriculture companies to set aside areas that remain unsprayed to allow the butterflies to breed. While there are few scientific studies on the subject, the practice of butterfly gardening and creating "Monarch Waystations" is commonly thought to increase the populations of butterflies.
For example, in the Washington, D.
Monarch butterflies go through four stages during one life cycle, and through four generations in one year. The four stages of the monarch butterfly life cycle are the egg, the larvae caterpillar , the pupa chrysalis , and the adult butterfly. The four generations are actually four different butterflies going through these four stages during one year until it is time to start over again with stage one and generation one.
In February and March, the final generation of hibernating monarch butterflies comes out of hibernation to find a mate. They then migrate north and east in order to find a place to lay their eggs. This starts stage one and generation one of the new year for the monarch butterfly. In March and April the eggs are laid on milkweed plants.
They hatch into baby caterpillars, also called the larvae. It takes about four days for the eggs to hatch.