monarch butterfly – Field Station /field-station/tag/monarch-butterfly/ UW-Milwaukee Wed, 25 Mar 2026 14:08:54 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 Monarch Butterflies – Spring, 2026 /field-station/bug-of-the-week/monarch-butterflies-spring-2026/ Wed, 25 Mar 2026 14:07:00 +0000 /field-station/?p=17002 Howdy, BugFans, THEY’RE COMING!!! It’s barely spring, officially – way too early to be thinking about butterflies, right? Nope.The first butterflies of the year have already been reported on the Wisconsin Butterflies website (Butterflies — wisconsinbutterflies.org) (which also serves your Tiger …

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Howdy, BugFans,

THEY’RE COMING!!!

It’s barely spring, officially – way too early to be thinking about butterflies, right? Nope.The first butterflies of the year have already been reported on the Wisconsin Butterflies website () (which also serves your Tiger beetle and Robber fly needs).

Our first butterflies are usually the anglewings (commas and Question Marks Anglewings (Family Nymphalidae) – Field Station) and the Mourning Cloaks Mourning Cloak Revisited – Field Station.Why? Because they go through the winter as adults, tucked up into a sheltered spot (called a hibernaculum).These are the species that are seen by people tapping maple trees in the Sugarbush during the warm days of late winter.When the cold returns – and it always does, except in the bizarre spring of 2012 – they seek shelter again.They are able to be abroad in early spring, before the wildflowers bloom, because they feed on sap from sap drips, juice from rotting fruits, and minerals from animal droppings.

The other early butterflies are species that overwintered as a chrysalis and emerged in spring – Cabbage Butterflies Cabbage Whites and Sulphurs Redux – Field Station and a couple of “blue” butterflies, the Eastern Tailed-Blue and the “Spring” Spring Azure Small Blue Butterflies – Field Station.In very warm years, early individuals of these species have been recorded in late March.Our first Monarch sightings usually come in May.

Back to the Monarchs. A year ago, winter censuses of the eastern and western populations, Monarch Butterfly showed that numbers were down The Monarch Butterfly Problem – Field Station. This year’s census found eastern Monarchs occupying 64% more territory in Mexico’s oyamel fir forests than last year.Not a home run, but reason for optimism .

Monarchs are on the way! Check the Journey North interactive map – .For more information, see .

Monarch caterpillar with black, white, and yellow stripes feeding on a green milkweed leaf

Mike Reese has built a wonderful community of butterfly-lovers who make reports to the Wisconsin Butterflies website; and while it is more anonymous, the Wisconsin Odonata Survey website () contains a treasure trove of information.Where do all those reports come from? Us – they are two examples of Citizen/Community Science projects here in Wisconsin! Register with the site, keep track of the butterflies and/or dragonflies/damselflies you see on your walks or in your back yard (you need to take a nose count of the butterflies but not of the dragonflies), and then log on to record what you’ve seen. Both sites accept pictures.  

The Journey North organization offers another Community Science project called the monarch larva monitoring project .

Go outside – look for butterflies!

The BugLady

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Autumn Adventures /field-station/bug-of-the-week/autumn-adventures/ Wed, 15 Oct 2025 14:20:23 +0000 /field-station/?p=16565 Note: All links are to an external site. Howdy, BugFans, The BugLady spends the spring and summer combing natural areas for bugs and flowers and other stuff to photograph, but in fall, she sits on a 10-foot-tall tower, counting migrating …

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Note: All links are to an external site.

Howdy, BugFans,

The BugLady spends the spring and summer combing natural areas for bugs and flowers and other stuff to photograph, but in fall, she sits on a 10-foot-tall tower, counting migrating raptors. As a result, her meanderings have mostly been confined to Forest Beach Migratory Preserve since September 1st. As the poet Stephen Vincent Benét once wrote (not about insects, but it could have been), “This is the last, this is the last, Hurry, hurry, this is the last,..” With some recent chilly nights and cool days, the Bug Season is winding down, poised for the first frost, but tree crickets and grasshoppers still sing on the prairie, and the late season flies, bees, butterflies, and dragonflies are afoot. Here are some September and early October bugs.

an autumn meadowhawk

AUTUMN MEADOWHAWK – Were there dragonflies? Indeed, there were! The last of the migrating darners and saddlebags passed the tower during a spell of Florida weather in September. Starting in early July, six species of meadowhawks occupy the second half of the dragonfly season, but they drop out, one by one until, in early October, only the White-faced and the Autumn (formerly Yellow-legged) meadowhawks remain.

Striped saddlebags

STRIPED SADDLEBAGS – And there was one very special dragonfly. Striped Saddlebags live south – way south. About their range, bugguide says, “Normal range from Northern Argentina to northern Mexico with regular movement into Arizona and Texas and more rare movement north and east as far as MN, WI, MI in the US and NS in Canada.” So it’s pretty exciting to find one!

western conifer seed bug

The WESTERN CONIFER SEED BUG is a large (¾”) and dapper member of the Leaf-footed bug family (Coreidae). People mistake it for the invasive Brown marmorated stink bug , but it’s slimmer than the chunky stink bug. WCSBs are typically found on conifers – when they’re not gracing the BugLady’s porch rail or trying to get into the house in fall (according to the Mass Audubon website, “They can also be easily captured and returned to the outdoors—bluebirds love them! There is no need to resort to insecticides. Chemicals are dangerous—Western Conifer Seed Bugs are not.” They don’t eat your furniture or house plants, but they do suck sap from and damage conifer cones, seeds, twigs, and sometimes needles. Originally a resident of the Pacific Coast, they have moved east (and have been exported (accidentally) to Europe). If your goal is natural forest regeneration, WCSBs are unwelcome guests. They may deploy a smelly chemical when alarmed.

monarch

MONARCHS – There’s a time, as the Blazing star (Liatris) is fading and before the New England aster starts up, when the prairie is yellow, and goldenrod nectar fuels migrating Gen 5 Monarchs on their journey south.

mourning cloak

MOURNING CLOAK – The migratory/Super generation of Monarchs lives a long time – emerging here in late August, overwintering in the mountains west of Mexico City, and getting at least part of the way back to Wisconsin in spring.Mourning Cloaks live even longer. A graph at the  website shows that sightings start in early March and run through the start of November, but unlike other species that produce several generations to span each season, there’s only one generation of Mourning Cloaks per year.

The Mourning Cloaks of spring have overwintered as adults, and as their caterpillar host plants (mainly willow, elm and birch) green up, they feed, breed, lay eggs, and die. Their eggs hatch and their caterpillars feed and pupate, and the butterflies emerge around the summer solstice. They feed for a while and then tuck themselves into a sheltered place to aestivate (become dormant) through the heat of summer. Yes – they start flying before the parade of spring flowers has begun, and yes, the next generation sleeps through the flowers of summer, but Mourning Cloaks are mostly indifferent to flowers. They get minerals from mud; they feed at sap drips (they’re often seen in the sugar bush in early spring, but they can become dormant again if winter revisits); they like rotting fruit, dung, and the honeydew produced by aphids, and they check the feeding holes created by Sapsuckers. By the time they lay eggs the next spring, they’re about 11 months old.

fiery skipper

FIERY SKIPPER – Good things come in small packages – this dynamite little butterfly is about an inch long, with an inch-and-a-half wingspread. Fiery Skippers are a mainly-Southern species that filters north into Wisconsin by mid-summer – a long haul on those short wings.

large milkweed bugs

LARGE MILKWEED BUGS (these are nymphs) come in Large, Small, and False. They’re in the Seed bug family Lygaeidae; they make their living by inserting their beak into the seeds within a milkweed pod, pumping saliva in to soften them, and sucking out the juices. They’re very social and don’t mind sharing a good food source, and it’s possible that adults send out some kind of chemical signal to attract other adults. Adult Large milkweed bugs can survive on non-milkweed seeds, but their nymphs can’t. They aren’t considered a pest unless you’re growing milkweed for seed, and they make a spectacular splash of aposematic/warning color .

Birds migrate, Monarchs and Common Green Darner dragonflies migrate, and so do Large milkweed bugs! It’s too cold here in God’s Country for them to overwinter in any form, so they repopulate the state in spring, after the milkweed is up. As with some birds, northern populations are long-distance migrants (and have longer wings to prove it) and southern populations don’t stray far from home.

bumble bee

A BUMBLE BEE busy collecting pollen for a brood that will not survive the winter.

false milkweed bug

The FALSE MILKWEED BUG looks like a Small milkweed bug (), and it’s even in the same genus, but it’s not sitting on milkweed. The BugLady usually finds them excavating the seeds of Ox-eye sunflower, aka the False sunflower. One note at says that if they checked their collection of Small milkweed bug pictures, they’d probably find a bunch of misidentified False milkweed bugs. Nice video of False milkweed bugs multi-tasking at the original BOTW, here . Their doppelgangers are poisonous/distasteful due to the toxic milkweed sap they ingest. False milkweed bugs are adorned in aposematic coloration, but as far as the BugLady knows, they are not poisonous/distasteful. Are they cashing in on predators’ predisposition to avoid red/orange and black? 

ant flight

ANT FLIGHT – A hatch of royal ants emerged from their digs in the pressure-treated wood at the edge of the hawk tower’s deck (not reassuring). The royal dance attracted to the deck three tree frogs that usually live around the base of the tower and perch on prairie flowers.

fork-tailed bush katydid

This FORK-TAILED BUSH KATYDID joined the BugLady on the tower and lingered for a portrait. The large curved structure, aft, is her ovipositor (the male has the “forked tail”). She inserts her eggs into a leaf edge, between the upper and lower surface of the leaf, or lays them on twigs or leaves. And there’s nothing out on the prairie that’s cuter than her jaunty, little nymph , . The BugLady is far more likely to see a Fork-tailed bush katydid than to hear one – as this site says, “Pffftt!” That’s all it is. There can be a lengthy pause between songs” .

black and yellow argiopes

BLACK AND YELLOW ARGIOPES, like some of the other orbweavers, get pretty hefty by the end of summer, alarming some folks. “Where did those huge spiders come from?” they ask. Answer – they’ve been here all along. They were smaller than the brightly-colored heads of push pins when they emerged from their egg sac in spring, and they’ve been eating ever since. 

tree hopper

This TREEHOPPER’s thorn disguise would be more effective if it were sitting in vegetation. Just sayin’. 

Buckeye Butterfly

BUCKEYE BUTTERFLY – Buckeye caterpillars  pick up a group of chemicals called iridoid glycosides from their foodplants. These chemicals stimulate their appetites so they eat and grow fast, but have the opposite effect on their predators, stunting their growth. 

Buckeyes are migratory, too, moving along coastlines and rivers, flying to the Deep South with a tailwind in fall and returning to us (a few generations later) in spring, with males arriving first.

Fun Fact about Buckeyes: flowers may change in appearance after being pollinated – maybe a clue as small as a localized color change. Researcher Martha R. Weiss did an experiment that demonstrated that a wide variety of wasp, bee, fly, and butterfly pollinators (including Buckeyes) can discriminate between “pre-change” and “post-change” flowers, and so can see which flowers will be more rewarding to visit – a win for both flowers and butterflies. 

Bonus points if you know where the Benét quote came from.

Go outside – look (and listen) for bugs!

The BugLady

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Monarch Miracle /field-station/bug-of-the-week/monarch-miracle/ Wed, 06 Aug 2025 16:38:40 +0000 /field-station/?p=16408 Howdy, BugFans, The BugLady was pecking away at this week’s episode when she had a “Hold the Presses” moment.BugFan Freda sent a series of pictures she had taken of a monarch caterpillar taking its first steps into the world (prefaced …

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Howdy, BugFans,

The BugLady was pecking away at this week’s episode when she had a “Hold the Presses” moment.BugFan Freda sent a series of pictures she had taken of a monarch caterpillar taking its first steps into the world (prefaced by the statement, “Who knew that monarchs also oviposit onto the flowers??”).So, this week, we start with a picture story, photographed and narrated by Freda (who has some serious photography skills and a lens that the BugLady can’t lift). The picture of the older caterpillar is the BugLady’s.

Said Freda, “It was amazing watching it chew its way out of the egg. It worked almost constantly and you could tell that it was putting forth major effort. Between its hand-like mouthparts and box-cutter-like forelegs, it was punching and chewing and slicing at an amazing pace for such a tiny thing.”

It looked like it wasn’t only busy chewing on the dry, outer edge, but there was also what appeared to be gelatinous stuff on the inside that it scooped up and worked into its mouth.] Imagine slurping up a slimy spaghetti noodle the diameter of your open mouth and having to use your hands to stuff it in. There were some pauses where you could almost hear it thinking, “I’m so stuffed, but gotta keep going – or die.” It seemed like a tremendous feat!” 

The gelatinous stuff was undoubtedly the last of the yolk material that nurtured it until it hatched.

“The caterpillar made it out and is resting now. : )

Newly hatched monarch caterpillar feeding on a milkweed leaf, with visible chew marks and small black frass (droppings) scattered nearby.

As of this morning, the ‘baby’ is 3 to 3.3 mm long. As the last photo shows, it’s been eating and pooping healthily.

Thanks, as always, for sharing your photography, Freda.

Monarch caterpillars have one pair of filaments on the front end and another on the rear end – anterior and posterior tentacles.According to Monarch Joint Venture, these tentacles are sensory, “The caterpillar’s tentacles are sensory organs. Caterpillar’s eyesight is poor, and tentacles are tactile. They aid in navigation on the front. They may also play a role in defense/predator confusion on the rear, leading a potential predator to think that the monarch’s rear is its head.” How do you tell one end of the caterpillar from the other (if, of course, it’s not eating)? The longer tentacles are in the front. There is also a tiny pair of actual antennae near the mandibles, to pick up olfactory signals and help the caterpillar find food. 

Quick review: the short-lived, early and mid-summer generations of Monarchs have one job – to goose the Monarch population.Hatch, eat, mate, lay eggs (and they’re doing a great job here this year).The final generation, sometimes referred to as Gen 5 or the Super generation, in the air from late-August on, have a different imperative – hatch, eat, metamorphose, and migrate (which is why they’re the only generation that’s tagged).How do they know what to do? The message comes in the form of old, leathery, bitter milkweed leaves (they prefer young and tender), fewer nectar plants, shorter day length, cooler nights, and the lowering angle of the sun (57 degrees above the horizon). And yes – we do see monarchs who seem not to have gotten the memo, flying in tandem at the end of the season. Apparently some of the penultimate generation may drift south, laying eggs as they go.

Freshly laid butterfly egg
The caterpillar starts to develop visibly within the egg, moving closer to the shell surface. Dark spots indicate the forming head capsule.
The caterpillar begins breaking through the top of the egg — the dark head is now pressing against the shell, starting to rupture it.
A close-up of the caterpillar’s head emerging from the egg — shiny and black, it pushes through the cracked opening.
The caterpillar has fully emerged from the egg and begins its journey to feed and grow.

They set their courses for a destination they’ve never seen, orienting themselves via the sun (with a dash of magnetic compass thrown in), with calculations so intricate that monarchs in Michigan, Maine and Montana set correct (but different) flight plans for central Mexico. And they find not only Mexico, but the overwintering spots in the mountains west of Mexico City.

And now a brief sermonette from the BugLady (Freda is not planning on fostering this infant until it forms and then emerges from its chrysalis, so she is exempt from the sermon). It has become popular to try to help the yo-yo-ing Monarch population by collecting eggs and hand-raising the caterpillars.The rationale (besides the facts that it’s great fun and very sciencey) is that the caterpillars are safer in a controlled, predator-free environment.

And indeed, they are, as long as their keepers practice good caterpillar hygiene, but caterpillars raised in the garage or basement or family room are not exposed to the environmental signals that will allow them to navigate properly. Some captive-raised butterflies do muddle through and arrive at their destination, but it’s a lower percentage than their wild-reared brethren.

The bottom line, if raising Monarchs is your thing, park them in the back yard. suggests that we could do a lot more for Monarchs if we would plant native milkweed for the caterpillars and native wildflower gardens that will bloom through the season for nectaring butterflies.

Go outside -watch the Monarchs!

The BugLady

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Monarch Butterfly Status Update /field-station/bug-of-the-week/monarch-butterfly-status-update/ Wed, 09 Apr 2025 14:12:30 +0000 /field-station/?p=16064 Howdy, BugFans, This is a Good-News-Bad News-Stay-Tuned kind of story.  But first, a little background.Besides being large and lovely, Monarch butterflies, of course, catch our fancy because of the death-defying migrations they undertake twice a year.Migrations – fueled by flowers …

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Howdy, BugFans,

This is a Good-News-Bad News-Stay-Tuned kind of story. 

But first, a little background.Besides being large and lovely, Monarch butterflies, of course, catch our fancy because of the death-defying migrations they undertake twice a year.Migrations – fueled by flowers – that carry some of them 3,000 miles from Canada into central Mexico.

Monarchs have a wide geographical range today, but only part of it is historic. They’ve been introduced or have found their way to and established populations in Hawaii (there’s a white subspecies in Oahu), some Caribbean Islands, Australia, New Zealand, and more, and they are accidental migrants to other spots on the globe. 

Most of the North American Monarch population is divided between the Western Monarchs that occupy the Pacific Coast west of the Rockies and overwinter in the southern half of California, and the Eastern Monarchs that range from the Rockies to the Atlantic Coast and overwinter in the oyamel fir forests in a mountainous area west of Mexico City. There are also pockets of Monarchs that are permanent residents in Arizona, around the Gulf Coast through Florida, and along the Eastern Seaboard as far north as Virginia.

monarch24 2rz

FIRST, THE GOOD(-ISH) NEWS.  Every winter the population of Eastern Monarchs that overwinters in the Mariposa Monarca Biosphere Reserve is censused by counting how many acres/hectares of the Reserve that they occupy (one hectare equals a little less than 2.5 acres or about two football fields). The 2024 survey found Monarchs on only 2.22 acres, one of the lowest densities since the count began in 1993, but in-2025, 4.42 acres were occupied. Good news but not great news – the population is still very low, and some researchers say that in order to be sustainable, the population should cover about 15 acres. 

Better weather, less drought, and better protections for the fir forests against illegal logging are credited with the increase (although, according to the Center for Biological Diversity, an ongoing threat to the forests is cutting trees in order to grow avocados for American tables).

Will this year’s boost become a trend? Monarch numbers tend to see-saw. On the negative side, a warming climate is rendering the mountainous Reserve less habitable for the firs and is making larger swatches of the South too warm for Monarch reproduction.  And then there are the pesticides that affect both the plants and the insects themselves. On the positive side, citizens along the butterflies’ path are getting the message about planting the milkweed needed by Monarch caterpillars and a variety of nectar plants for the adults. For more background on Monarch populations, see here.

monarch cat22 3rz

THEN THE BAD NEWS. Western Monarchs, historically numbered in the millions and whose numbers had exceeded 200,000 in recent counts, suffered a major crash this year, with the 2024-2025 survey finding just over 9,000 butterflies. The “break-even” number for survival of the Western Monarch may be as high as 30,000, and some scientists put them at a 99% probability of being extinct by 2080.

A recent study shows a 22% decline in butterfly numbers across multiple species over the past twenty years.

AND THE STAY-TUNED NEWS. A few years ago, there was some momentum to list Monarchs as Threatened under the Endangered Species Act (ESA). An “Endangered” designation means that a species is in danger of going extinct over all or part of its range, and a “Threatened” species is one that is likely to become Endangered within the foreseeable future over all or a significant portion of its range. For that story, see here.

For various reasons, among them the fact that Monarch numbers can vary dramatically from year to year, the decision was kicked down the road. Then, in 2024, the U.S. Fish and Wildlife Service (USFWS) again proposed listing the Monarch. The deadline for public comment, initially set to expire in March, was extended until May 19, with a possible decision to be announced by the end of 2025. If accepted, the Monarch would be the “most common” Threatened species ever listed, which causes some observers to say that it’s still too early to bring them under the ESA umbrella.   

Monarchs are already listed as Endangered in Canada and are recognized as a Species of Special Protection in Mexico.

monarch20 34rz

Listing a Threatened or Endangered Species has far-reaching ripples, both monetary and regulatory (land use restrictions, for example), and requires a Solomon-like crafting of the law. Any species added to the list must have a budget and a realistic game plan for recovery – one that, in the case of the Monarch, would attempt to turn back the clock on decades of habitat loss and degradation, pesticide use, and the effects of climate change. Changing weather patterns have exposed spring migrants to stormy weather, and warmer falls have caused many Monarchs to linger in the north.  

Ideally, people should embrace the conservation goals of a recovery plan voluntarily, and any plan should allow for the continuation of state and local efforts by individuals, agencies, and organizations. Too rigorous, and people will resent it and it will become a political hot-potato; not rigorous enough and the plan will fail the species.  In the case of the Monarch, both the butterfly and its remarkable migration are in peril. 

Fun Fact about Monarchs: they were the first butterfly species to have its genome sequenced.

monarch22 12rz

Another Fun Fact about Monarchs:  the name “Monarch” is thought to be a reference to 17th century British King William III, also called the Prince of Orange (the British royalty/peerage also figured into the naming of the Baltimore Oriole and the Baltimore Checkerspot butterfly after Lord Baltimore, whose servants sported orange and black livery). 

Yet Another Fun Fact about Monarchs: according to Wikipedia, they’re the state insect of Alabama, Idaho, Illinois, Minnesota, Texas, Vermont, and West Virginia, and there were unsuccessful attempts in 1989 and 1991 to name them the National Insect of the United States.  

Final Fun Fact about Monarchs: THEY’RE COMING! .

The BugLady

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The Monarch Butterfly Problem /field-station/bug-of-the-week/the-monarch-butterfly-problem/ Wed, 27 Mar 2024 14:33:10 +0000 /field-station/?p=14704 Note: Most links leave to external sites. Howdy, BugFans, The BugLady wrote this for an upcoming newsletter of the Lake Michigan Bird Observatory (an organization that would love your support). It started out as a simple report about this year’s …

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Note: Most links leave to external sites.

Howdy, BugFans,

The BugLady wrote this for an upcoming newsletter of the Lake Michigan Bird Observatory (an organization that would love your support). It started out as a simple report about this year’s survey of overwintering Monarch Butterflies, but then it took the bit in its teeth and became oh-so-much more. Put your feet up. 

butterflies on branches

Every fall, most of the Monarch Butterflies east of the Rockies set their compass for a small patch of mountains just northwest of Mexico City.This winter’s count of eastern Monarch Butterflies (Danaus plexippus plexippus) overwintering in the oyamel fir forests of central Mexico was the second lowest since annual censusing began in 1993. In the 1990’s, the eastern Monarch Butterfly population was estimated at 70 million, and today’s numbers represent an 80% decline in population.

The census is not an actual nose-count of the butterflies themselves but is a measurement of the area they occupy.They’re densely concentrated on their wintering grounds — scientists estimate between 20 and 30 million Monarchs per hectare (about 2.5 acres).The lowest area, 0.67 hectares (1 66 acres), occurred 10 years ago, and the largest ever, in 1996-97, found 45 acres occupied.This year, Monarchs were seen on 0.9 hectares (2.2 acres), down 59% from the 2022-2023 season (Dr. Karen Oberhauser, founder and director of the , points out that 2.2 acres is smaller than two football fields).It’s felt that almost 15 acres of overwintering butterflies are needed to maintain a healthy eastern population.“Monarch populations [are] at a level that most scientists suggest is not sustainable,” says Dr. Oberhauser.Western Monarchs, residents and migrants along the Pacific Coast, are treated as a separate population.   

Migration is expensive, energy-wise, and is dangerous, and the list of hazards is long.Land use changes and habitat loss, herbicides and pesticides, loss of milkweed, car-butterfly collisions, climate change that brings harsh winter conditions to central Mexico or storms as the butterflies prepare to depart, or that puts migrating butterflies out of sync with nectar plants on their spring migration, high temperatures that reduce the nutritional value of milkweed plants, and severe drought along the fall migration route through “the Texas Funnel” have all been suggested as factors.

The integrity of the fir forests themselves is critical, but the illegal logging that has reduced the forest size and cover in the past was held to a minimum last year.The butterflies depend on a dense forest to act as insulation so they don’t have to expend as much energy staying warm, dry, and hydrated.

butterfly on a flower

Quick review of Monarch biology and migration — there are four or five generations annually, and the last brood of the year is extraordinarily long-lived for a butterfly. It emerges in August or September, and while the earlier generations are reproductively active, this final generation is not. Signaled by decreasing day length, lowering angle of the sun, cool nights, and increasingly leathery milkweed leaves, their reproductive organs don’t mature.Instead, they apply their energy to a journey – a leisurely trip that can cover more than two thousand miles and take two months.The butterflies feed on nectar from a wide variety of flowers as they wend their way south, and while a newly-emerged Monarch in Wisconsin has about 20 mg of fat in its body, a Monarch newly-arrived in the oyamel fir forests of Mexico may carry 125 mg of fat.They eat little on their wintering grounds.

monarch egg

With the warming temperatures of late March, they become reproductively ready and head north through northern Mexico and our Southern states, laying eggs as they go, careful not to get ahead of the emerging milkweed plants.Their young — the first-generation offspring of the Mexican butterflies — keep moving and recolonize the north, often arriving in Wisconsin in mid-May and in Canada shortly after that (Southern summers are too hot for the caterpillars to thrive).

caterpillar on a flower

Their offspring – the second generation out of Mexico, continue to lay eggs and may fly a little farther north, but most have reached their destinations by the end of June.The “job” of this short-lived generation (and of the next generation, if there’s time for one) is to stay put and use their energy to build up the population. The migratory final generation, sometimes called Gen 5 or the Super Generation, is the only one that is tagged.

tagged butterfly

This complicated dance depends on good weather, milkweeds for caterpillars, and abundant nectar plants for adults. Monarchs will lay their eggs on a variety of milkweed species, but Common milkweed is the favorite.

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There have been passionate efforts in past years to list the Monarch as an Endangered Species under the Endangered Species Act (ESA).Classification under the ESA is a lengthy process, there are many other deserving candidates, and listing requires both a recovery plan and a dedicated budget.  

Monarch populations are subject to wide swings, but a low year followed by another low year lessens the possibility of a speedy comeback.Overall population levels in the summer of 2023 were not alarming, but severe heat and drought in the Texas Funnel migratory corridor probably resulted in fewer Monarchs finishing their journey to Mexico.

Based on a few recent studies, there are voices, even voices within the Monarch Butterfly community, that suggest (counterintuitively) that there’s no need to change the Monarch’s status, citing past population plunges and recoveries.The International Union for Conservation of Nature (IUCN), a leading scientific authority on the status of species, recently downgraded Monarchs on their Red List of Threatened Species from Endangered to Vulnerable.

Some of the arguments are historical. Monarchs like milkweeds, and milkweeds like sunshine, and the treeless Great Plains is thought by some to be the historical center of both Monarch and milkweed populations.Too, there was lots of sunshine during the long postglacial period while trees moved back north after the most recent glacier pushed them south, and some speculate that milkweeds and Monarchs took that opportunity to push east and increase their numbers before the forests regrew.

The early settlers cut down swathes of America’s Great Eastern Forest to establish villages and farms, making the area sunnier and more Monarch/milkweed-friendly, and some say that Monarch populations are larger now than they were 200 years ago.Today, they say, Monarchs are adapting to modern stressors, and they’re establishing some non-migratory breeding communities in Florida and around the Gulf Coast.Monarchs, some scientists say, are not at risk, but the eastern Monarch migration may be (a distinction without a difference to Monarch lovers).   

Did the Monarch’s eastward expansion into a glacially-modified landscape and later into a human-modified landscape artificially boost their numbers, so that what’s happening today is just a “course correction?” Should we base the butterfly’s status on the wintering numbers rather than the summertime population? On today’s numbers vs long-time averages? Is it better to err on the side of caution?” Will there, as Chip Taylor of Monarch Watch says “always be Monarchs?”

Only time –- and more research — will tell who’s got it right. In the meantime, what can we do to help? 

  • Plant native, not tropical, milkweeds for caterpillar host plants.The tropical milkweed Asclepias curassavica may discourage migration and encourage disease, and the toxins in its sap may be a ;
  • Plant lots of native nectar flowers that will bloom throughout the summer for the butterflies;
  • Reduce or discontinue pesticide use;
  • The urges us to put our efforts into habitat improvement rather than into the captive rearing of caterpillars;
  • .

The BugLady

The post The Monarch Butterfly Problem appeared first on Field Station.

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Closed for June – The Dark Side /field-station/bug-of-the-week/closed-for-june-the-dark-side/ Wed, 30 Jun 2021 15:37:15 +0000 /field-station/?p=12309 Howdy, BugFans, It’s the last post of June and the final “do-it-yourself” BOTW for a while. Here are some stories about some of the seamier aspects of bugs. OK – this is like watching a train wreck. Enjoy the video …

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Howdy, BugFans,

It’s the last post of June and the final “do-it-yourself” BOTW for a while. Here are some stories about some of the seamier aspects of bugs.

OK – this is like watching a train wreck. (be sure to suit up).

And another train wreck – once upon a time, when asked about the issue of non-native species, an (unsuccessful) candidate who had been proposed as head of the Department of Interior said that we lose species and we gain species, and it all balances out – what’s the problem?

Monarch migration – small bug, big sky, huge stakes.

An of monarch migration.

Disclaimer. The BugLady doesn’t follow his blog, but the July 4 weekend is upon us (lots of outdoor activities) and the BugLady recently saw a local TV station’s obligatory “It’s-going-to-be-a-bad-summer-for-mosquitoes-folks” feature – never mind that we were then in a moderate drought, with no puddles anywhere. Anyway, has some serious scientific chops, and the BugLady doesn’t like collateral damage. Use chemicals sparingly, or better yet, put them on yourself, not your lawn.

The BugLady

The post Closed for June – The Dark Side appeared first on Field Station.

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