Bug o’the Week – Morning Glory Prominent Moth

Howdy, BugFans,

As she cruises through her moth books trying to identify what she’s photographed, the BugLady sees pictures of AMAZING caterpillars – not drab brown or grass-green caterpillars, but caterpillars that eschew camouflage in favor of some pretty gaudy togs (she has a Caterpillar Wish List that may require a Caterpillar Road Trip).  For example:

The Imperial moth https://bugguide.net/node/view/7718;

The venomous Crown Slug https://bugguide.net/node/view/1434824/bgimage;

The astounding Hickory horned Devil https://bugguide.net/node/view/1550971/bgimage and https://bugguide.net/node/view/1757001/bgimage and https://bugguide.net/node/view/1757013/bgimage and https://bugguide.net/node/view/1757026/bgimage and https://bugguide.net/node/view/992138/bgimage;

The Faithful Beauty https://bugguide.net/node/view/6266;

The Curve-lined Owlet https://bugguide.net/node/view/862030/bgimage;

The Fawn Sphinx https://bugguide.net/node/view/1785681/bgimage;

The Paddle Dagger https://bugguide.net/node/view/1825/bgimage; and

The Bravo https://bugguide.net/node/view/1895198/bgimage.

Some brightly-patterned caterpillars advertise their toxicity, but others blend in because their color patches break up the outline of their body.

She thought she had checked off one of the caterpillars on her list this summer.  It was head-high and moving smartly up a tree trunk at the Bog when she saw it, and her preliminary (and secondary) ID was a Unicorn moth caterpillar.  Then she checked other genus members and changed her mind (and is hoping that she dodged a “publish in haste; repent at leisure” moment).  It’s (probably) the closely-related Morning-glory Prominent (Schizura ipomoeae) (Ipomoea is the genus of morning-glory).  Unicorn caterpillars lack the striped head and that extra hump on mid-abdomen that the Morning-glory Prominent has, and the hairs on their abdomen are shorter.  Here’s a better shot of the Morning-glory https://bugguide.net/node/view/1292330/bgimage, and here’s the Unicorn https://bugguide.net/node/view/1446998.

No road trip is needed for the Morning Glory Prominent – it lives in deciduous woodlands across the US and southern Canada.  One reference called it “common,” and it well may be, but both caterpillar and adult are awesomely camouflaged.

There are eight species in the genus Schizura in North America north of the Rio Grande.  They’re in the family Notodontidae (the Prominent moths), a family that, according to Wagner in Caterpillars of Eastern North America “includes many of the most handsome and behaviorally interesting caterpillars in the temperate zone.”

Notodontid/Prominent caterpillars are pretty cool.  They’re big, with large heads, and some sport a variety of lumps and spines and decorations on their sometimes-whimsically-shaped bodies.  You can find them perched on leaves in the daytime.  Maybe.  A “work-around” practiced by some Notodontid caterpillars involves girdling a tree stem and spreading liquid on the cuts; substances in the liquid depress a plant’s usual chemical defenses to grazing.

Caterpillars in the genus Schizura have a gland that produces a mixture of formic and acetic acids along with “lipophilic” (fat-loving) compounds.  This concoction is delivered as a spray that the caterpillar can direct with accuracy up to six inches away.  The gland is located right behind the head, and the spray comes through a slit in the “neck” (though some sources said it was in one of the humps).  In his write-up about the Unicorn caterpillar in Moths and Caterpillars of the North Woods, Sogaard says that these glands may be so large that they “can occupy a tenth of the caterpillar’s volume,” and the BugLady assumes the Morning-glory Prominent is similar.  The lipophilic compounds help the liquid to spread on and penetrate the victim’s exoskeleton/skin (it can raise a painful blister on humans).

Adult Morning-glory Prominents have wingspans of 1 ¾” and they’re somewhat variable in color http://mothphotographersgroup.msstate.edu/species.php?hodges=8005.  A rolled-up posture https://bugguide.net/node/view/404222/bgimage makes them look like broken twigs.

According to bugguide.net, caterpillars of the Morning-glory Prominent “feed on the leaves of beech, birch, elm, maple, oak, rose [including apple trees], and other woody plants; probably not on morning-glory.”  Which is probably why it has alternative names like False Unicorn Caterpillar and Checkered-fringe Prominent.  They are gregarious as young caterpillars and loners later – the young caterpillars feed on the leaf’s under-surface, skeletonizing it; and the older stages eat inward from the leaf edge, carving a half-circle out of the edge and curling into it, looking like a damaged leaf https://bugguide.net/node/view/1615595/bgimage.  They overwinter in suspended animation as pre-pupae, ready to pupate in spring.

Kate Redmond, The BugLady

Bug of the Week archives:

The Uncommon Beauty of the Oak Opening

I must admit, when I first encountered an Oak Opening, I had a hard time initially wrapping my brain around what was unique about the habitat. I looked up and could recognize that it contained oak trees, standing high in their far-reaching, craggy-branched splendor. “Ok, they’re oak trees,” I shrugged. Then one day it dawned on me: an Oak Opening possesses a vast amount of open space compared with what I understood a forest to look like.

A great distance of space can exist between trees, sometimes 100-feet from one another. This is why these habitats are also known as “Oak Openings,” and is the name for this one-acre area at Riveredge Nature Center overlooking the Milwaukee River. This portion of the property also boasts uniquely untilled original soil and a rarely seen guild of native plants. But what else is unique about Oak Openings?

The Oak Opening, as the name suggests, is a surprisingly open forest.

Oak Openings have become incredibly rare

The numbers of Oak Savanna (a somewhat similar habitat with less tree density than an oak opening) previously standing and currently in existence are staggering. Of the 5.5 million acres that once existed, according to the Natural Heritage Inventory, less than 500 acres exist that had plant assemblage similar to the original Oak Savannas. Similar to savannas, Oak Openings are one of the rarest and most threatened habitats in the world. Summarily, many of the plant and animal species that flourished in these systems have perished, or their populations have taken hits as they struggled to find other, less suitable habitats.

Autumn Oak leaves in the sun at Riveredge

Pre-settlement, wildfires and fires set by Native Americans took place across the US throughout the year, burning off smaller trees and invigorating understory plant seeds to sprout. Oaks have thick bark and a deep taproot, which equips them uniquely to tolerate fires more than other woody species. After a fire the only plants that stood throughout the charred landscape were oak trees, such as Bur Oak.

What happened to Oak Openings?

Prior to settlement, about half of Wisconsin was covered in Oak ecosystems (such as oak woodland, oak savanna, oak opening). When settlers moved west into this territory, these oak ecosystems appeared, and proved to be ideal areas for farmland and more readily cleared than a dense forest. Many of the soils were rich in nutrients after centuries of plants and animals had built up the soil. The removal of indigenous peoples, their customs, and traditional ecological knowledge, as well as the removal of fire fuel continuity by turning over original ground with the plow, worked to suppress fires that had been previously afforded greater affect on the landscape.

The Riveredge Maple Sugarbush, across Highway Y from the Oak Opening.

Oak trees provided ideal building material for houses and barns, and if any was left over it became firewood. Millions of linear board feet would be shipped to become furniture, tool handles, and flooring throughout cities such as Milwaukee. While the wood lasted, logging was a bustling business in Wisconsin.

In areas of Oak Savannas that still stood, without fire management or grazing by wild or domesticated animals, smaller trees would begin to grow up between oaks, competing for sunlight and rain. Invasive species such as Buckthorn would begin to fill in areas that were previously the domain of native plants that grow more slowly. When we picture a forest, this, comparably more cluttered, landscape is likely what we imagine.

Today, an oak opening gives the same reprieve from a forest’s overstory as it always has; however, it now represents some of the best of what many areas have lost. For ecologists, oak openings and other similar rare habitats now act as living libraries of species and their interconnected assemblages, to reconstruct in our restoration efforts.

This summer, experience Wisconsin’s natural heritage by visiting the Oak Opening at Riveredge Nature Center, and continue visiting throughout the seasons. This location is also one of our most picturesque locations from which to view the Milwaukee River. In this now uncommon location, you can experience the tranquility that can only be found within trees that live for hundreds of years.

Overlooking the Milwaukee River from the Oak Opening at Riveredge Nature Center.

What’s Blooming at Riveredge? An Updated Phenology Report

One of the fantastic Riveredge volunteers, who has been exploring Riveredge trails for years to both take photographs and record observations, is letting us know what she sees blooming at Riveredge. In scientific terms, this is called “Phenology.” What is phenology? It’s very similar to another word, phenomenon. Phenology means what happens, and when, in nature. Some of the most common examples are: when flowers are blooming, when buds are present, when specific migratory bird species return, when birds are nesting.

Chances are, you already notice phenology you just might not call it that. If you notice when your garden is blooming, when the trees are budding, or when butterflies return to the skies – you’re observing phenology! Read below to learn what you can find along the trails when you visit Riveredge Nature Center right now.

Spiderwort can be seen throughout Riveredge prairies.

In Bloom

Bullhead Lily
Blue Flag Iris
Canada Anemone
Tall Meadow Rue
Fragrant White Water Lily
Lance Leaved Coreopsis
Hairy Beardtongue
Blue Wild Indigo
White Wild Indigo
Hoary Alyssum
Prairie Golden Aster
Common Cinquefoil
Cow Parsnip
Large Flowered Beardtongue
Wild Garlic
Spreading Dogbane
Northern Bedstraw
Pale Purple Coneflower
Tall Beardtongue
White Avens
Poke Milkweed
Heal All
Pale Spike Lobelia
Black Eyed Susan
Wild Quinine
Wild Four O’Clock

Pale Purple Coneflower

Flower in Bud

Wild Leek

Diversity Outdoors

Dear Riveredge Family,

On June 5, we shared our reflections and solidarity on the movement to end systemic racism in our society  on our social media channels and website

“As a historically and predominantly white-led environmental organization, we realize there is much ground to cover in diversifying the outdoors, and many reasons why Black Americans and People of Color haven’t always felt welcome in wilderness spaces. We support the Black Lives Matter movement and the need for systemic change in our society. Riveredge Nature Center is a sanctuary where each person can embrace, celebrate, and revel in experiencing the wonders nature has to offer. We pledge to continue to improve the way we make these opportunities available to better serve our communities.

Black Lives Matter. Black Birders Matter. Black Experiences Matter.

Education is an ongoing process, and in-step with the Riveredge inquiry-based philosophy, we’re always trying to improve our understanding of our place in the world and how we can better serve the outdoor adventure community.”

Since that time, we have all continued to reflect on our beliefs, personal biases, privileges, and the realities of experiences that are unfamiliar to us. To be part of a community of change, we must first change ourselves. 

The environmental and outdoor fields have struggled, and continue to struggle, to engage and serve Black people and People of Color. The way our society arrived at the outdoors and nature being inherently NOT a privilege for all extends back to the very moment these remarkable tracks of wilderness and wild spaces were created as such, and for whom they were intended to serve at that time. We encourage you to visit Diversify Outdoors to hear for yourself stories from those who have been distanced and separated from the natural world. 

James Edward Mills, climber, journalist, author, and Madison, Wisconsin resident briefly outlines some of the reasons behind this legacy in his book The Adventure Gap:

“Historical reasons may also account for why some African-Americans don’t take pleasure in outdoor experiences. After four hundred years of slavery and forced outdoor labor, African-Americans migrated en masse to major US cities after the Civil War and the end of slavery. Even more left the rural communities of the South during the Great Depression. Jim Crow laws and other forms of discrimination restricted movement and segregated minorities to urban enclaves until the Civil Rights Act of 1964. White supremacist groups typically perpetrated their acts of violence against minorities in wooded areas beyond city limits. Given this legacy, it’s no wonder that African-Americans have often preferred to remain close to home.” 

Mills elaborates on how these factors influence current day demographics: 

“A 2010 Outdoor Recreation Participation survey conducted by the Outdoor Foundation reported that of 137.8 million US citizens engaged in outdoor activities, 80 percent were Caucasiona, a trend that is also reflected in the demographics of those who chose wilderness protection as a career. The National Park Service reported in 2010 that white men occupied 51 percent of positions at that agency and white women, 29 percent. These numbers are similar to those of other land and resource management agencies, such as the Bureau of Land Management and the US Forest Service. 

These statistics become significant when compared against the demographic profile of the nation as a whole. According to Dr. Nina Roberts, an assistant professor and social scientist from San Francisco State University, though African-Americans represent 12.6 percent of the US population, they typically make up a lower proportion of national park visitors (around 5-6 percent, depending on the region). Even with a sharp increase since 2006, “minorities still remain well below the number of visits of their white counterparts in proportion to their population across the United States,” says Roberts.”

At Riveredge, we work every day to connect our communities with the outdoor world, and we know that we must do our part to help bridge this gap. 

We do not yet have a complete list of specific action steps that we will take to correct our own struggles in serving communities of color. But we do want you: our neighbors, members, and friends, to know that we have begun this work. Over the past year, the Riveredge staff team has engaged in diversity, equity, and inclusion (DEI) training with the intent to create lasting organizational change in the coming months and years. Within our staff and Board, we are working on plans to further accelerate and prioritize this overdue work. Our goal is to create change within our organization and contribute to change within the culture of outdoor access and environmental education  in the coming year and years to come. 

We know we can do better. We will do better. It will take all of us. And the time is now. 

We will continue to keep you apprised of our progress, invitations for involvement, and action to further our growth as an organization and continue our work to serve our communities more effectively each and every day. 

With Great Gratitude,

Jessica Jens, Executive Director

Elizabeth Larsen,  President, Board of Directors

Bug o’the Week – Fiery Skipper Butterfly

Greetings, BugFans,

The Fiery Skipper is one of a pair of distinctive skippers that was featured in a BOTW in 2013 (https://uwm.edu/field-station/fiery-and-common-checkered-skippers-family-hesperiidae/).  It’s an uncommon migrant to Wisconsin, but the BugLady saw 11 Fiery Skippers decorating the vervain flowers at Waubedonia Park recently, and they seem to be having a good year statewide, so she decided they deserve a more complete biography.

Skippers, so-named for their rapid, bouncy flight, are butterflies that the Field Guide to Butterflies of North America refers to as a “group of mostly small and confusing creatures” (the majority of skippers are either brown and orange or orange and brown).  They are not moths, but they are often called “moth-like” because they are big-eyed, hairy, and chunky.  Their short-wings have to work extra hard to propel them through the air (at speeds up to 20 mph, according to one source).  Skippers have sometimes been called a transition group between butterflies and moths, but a genetic work-up places them squarely in the Superfamily Papilionoidea along with Monarchs, Tiger Swallowtails, Red-spotted Purples and the rest.  Their antennae are different than a moth’s – ending with an elongate, hooked knob.

They are not moths, and the BugLady is dismayed when someone who should know better, like the University of California Department of Agriculture and Natural Resources Statewide Integrated Pest Management Program, says in a publication about lawn pests that “Fiery skipper adults resemble butterflies and…..”  Or when an article in the Journal of the Acadian Entomological Society in 2012 says “The Fiery Skipper (Hylephila phyleus Drury, 1773) … is a medium-sized skipper … commonly found on both American continents. Moths typically fly from early September to late October” [emphasis, the BugLady].

Here’s a nicely illustrated “how-to” (though the BugLady was dismayed to learn that there are skippers in Australia, too) https://australianbutterflies.com/whats-difference-butterflies-skippers-moths/.

Fiery Skippers are in the skipper family Hesperiidae and the subfamily Hesperiinae, the Grass skippers (because their larvae eat various kinds of grass).  Grass skippers often sit with their front wings spread partly open and their hind wings a little less so.  Kentucky bluegrass is among the grasses on the Fiery Skipper caterpillar’s menu, and it’s considered a pest species in some areas because of the patches of dead, brown grass where caterpillars feed.  Caterpillars live on grass blades that they fold/roll lengthwise and web into a shelter.  Several sources pointed out that these shelters lie horizontally, close to the ground, below the blade of a lawn mower.  They pupate on the ground, and the adults emerge with only one thing on their mind – females immediately start scoping out good habitat for their eggs, and males sit on the tops of grasses watching for them.  Most reproductive activity takes place within their first few days as adults.  Here’s a nice set of pictures of their life cycle https://bugguide.net/node/view/452219/bgimage.

There is a lot of variation within the species; females’ wings https://bugguide.net/node/view/233966/bgimage are more patterned than males’ https://bugguide.net/node/view/1720496/bgimage, and females can be notably un-fiery https://bugguide.net/node/view/126346/bgimage.

Sometimes, when the BugLady is collecting information for a BOTW, her subject lets her know what story it wants her to tell.  In the case of the Fiery Skipper (Hylephila phyleus), the story seems to be about where it lives.  Not in the short term – day-to-day it’s found in sunny, open spaces, often gardens, with flowers to nectar on and grass nearby for the larvae, from Canada to Argentina (with gaps in the Great Plains, Rockies, and Great Basin).  But this is a largely southern-to-tropical butterfly that none-the-less migrates from the southern/resident portions of its range to the northern US and into Canada in varying numbers from year to year.

And that’s a relatively new phenomenon.  According to the Massachusetts Butterfly site (whose data encompass 200+ years), the first Fiery Skippers were recorded in that state in 1940 (Rhode Island in 1911, Canadian Maritime Provinces in 1947).  In Butterflies of Wisconsin (1970), Ebner tells us that the earliest state records here were in 1952 and 1957.  He notes that the specimens “were rather fresh, perhaps being introduced here by stragglers that ventured into Wisconsin earlier during the same summers and layed [sic] their eggs.

In the south, around the Gulf of Mexico and in the desert southwest, they breed most of the year.  The butterflies that arrive here in early summer probably produce one brood that lives through the summer, but it’s too cold here for their caterpillars to survive the winter.  It’s possible that patterns connected to climate change are enhancing the weather that supports the Fiery Skipper’s tendency to travel, and it’s probable that the regions where caterpillars of this exquisite butterfly can overwinter will extend north.

A resource that the BugLady regularly checks includes a section on economic impact in its species information.  Fiery Skippers were given a plus for benefitting local economies via eco-tourism.  Butterfly fans in northern states may travel to Fiery Skipper sites in big years – indeed, the Massachusetts Butterfly folks initially scheduled field trips to the most reliable sites for the skipper.

Nota Bene: one of the hits that came up as the BugLady researched the Fiery Skipper was a range map on the Moth Photographer Group’s site at Mississippi State http://mothphotographersgroup.msstate.edu/large_map.php?hodges=4013.  She thought it might be another one of those skipper/moth deals, but it turns out that the group posts range maps for butterflies, just as they do for moths, but not pictures.  Good resource.

And this, by the BugLady’s count, is (drum roll) BOTW #550!

Kate Redmond, The BugLady

Bug of the Week archives:

Blooming Spring Flowers at Riveredge

Lesser Yellow Lady's-slipper at Riveredge Nature Center

Spring flowers are flourishing right now at Riveredge! These are known as ephemerals, meaning they won’t last long – so get here to experience these beauties soon!

Great White Trillium Trillium grandiflorum has been blooming for a few weeks along the Milwaukee River trails. “But that flower isn’t white?!” you say? Indeed! As trillium flowers age, they commonly turn pinkish or purple before the petals wilt.

Golden Alexander at Riveredge Nature Center

Golden Alexander Zizia aurea is one of the spring flowers blooming along the trails at Riveredge. It might not be immediately obvious, but this forb is in the carrot family.

Wild Geranium

Wild Geranium Geranium maculatum is blooming throughout forested areas. This herbal plant has been used for pain relief throughout history.

Another example of Wild Geranium, this image better displays the vascular structure of the petals.

Swamp Buttercup Ranunculus septentrionalis can be found throughout our moisture-rich lowlands. It can easily be confused for Marsh Marigold, but its flowers are much more pointed.

Lesser Yellow Lady's-slipper Orchid

Lesser Yellow Lady’s-slipper Cypripedium parviflorum var. makasin, or Small Yellow Lady’s-slipper, is one of the more elaborate flowers, so named because of its appearance (the image above may show a better angle of the slipper appearance. Learn about our Native Orchid Restoration Project here.

Small Yellow Lady's-slipper

Sometimes, don’t you just feel like a third slipper?

Prairie Smoke

Blooming Spring Flowers in the Prairie at Riveredge

Wild Columbine

One Wild Columbine Aquilegia canadensis was observed blooming in a shady spot adjacent to the dry prairie at Riveredge.

Prairie Smoke

Prairie Smoke Geum triflorum is springing up from the soil, but hasn’t yet opened to show the wispy tassels for which it is named.

Prairie Shooting Star

Prairie Shooting Star Dodecatheon meadia is just beginning to blossom in a few spots. This flower is easy to distinguish because it looks like it’s pointing to the ground.

Native Orchid Restoration Planting at Riveredge

Riveredge volunteers and staff, along with employees of Stantec, gathered to plant seedlings that will become the basis of our native orchid restoration project. Stantec, Smithsonian – North American Orchid Conservation Center, Sheboygan County, and Wisconsin Coastal Management Program are all partners in this wide-ranging orchid restoration project. Thank you to our friends at Sheboygan County, as well as American Transmission Company, for generously providing materials and labor to build the Orchid Shade House where these plants are being raised!

Melissa Curran of Stantec is the leader of this orchid restoration project throughout the Midwest. She explains to volunteers how to plant orchid seedlings in pots inside the Orchid Shade House at Riveredge.

The Journey of an Orchid Seed

Orchids seeds begin as tiny, difficult to see specks the size of dust, and are dispersed through the wind. Minnesota Landscape Arboretum propagates and provides the seedlings for this project.

Many people may not realize that orchids are native to the Midwest. Orchids throughout this region are terrestrial, meaning that these orchids grow in the soil. Epiphytic orchids, the types that grow with aerial roots, are more commonly known.

Terrestrial orchids have complex fungal relationships, and certain species of orchid seedlings will only grow with the help of certain species of fungus. These species relationships are still a part of the mystery scientists are trying to solve. In the interim, seedlings are raised in a media culture, which provides nutrients and functions as a surrogate fungal connection.

These orchid seedlings grow in clumps and have to be pulled apart delicate care.

A soil combination is mixed, which drains quickly and doesn’t retain more moisture than the plants prefer.

Thank You Orchid Restoration Volunteers!

Thanks to everyone who helped us plant our orchid seedlings! Many hands makes light work – if you’d like to volunteer to help restore orchids throughout the Midwest, learn about volunteering at Riveredge.

One orchid seedling is planted in every pot. These plants will harden off to become acquainted with the natural conditions in the wild inside our Orchid Shade House.

Of course, once the orchids are potted, that ever important ingredient – water! We’re still looking for volunteers to help water these fledgling flowers.

And voila! Two weeks after the initial planting a sea of orchid seedlings sprout their first leaves inside the Orchid Shade House! Some of these flowers will be planted at suitable locations throughout Riveredge. Many of the orchids are destined to be planted throughout the Midwest in habitats where they are likely to flourish, or will bolster or reestablish orchid populations that have existed historically.

Milwaukee Journal Sentinel visited to chronicle our orchid planting day, read their story about the project here.

Fostering the Flowers of Tomorrow: Native Orchid Restoration at Riveredge

If a canary is a health gauge for air quality in a coal mine, then one might consider our native temperate orchids a gauge for the health of our native plant communities.

Judy Larsen, spouse of the first Riveredge employee Andy Larsen, remarked that when they arrived to Riveredge 50 years ago, she observed a healthy orchid population, including a prominent grouping of Yellow Lady’s Slipper along the Milwaukee River. Yellow Lady’s Slipper has since been extirpated. White-tailed Deer are known to prefer this species, and the large herd size could be part of the reason behind its disappearance. Today, we have three known orchids on the property and are working to support these remaining species.

By researching our ‘canaries’ we hope to better understand the variables that individual orchid species need for success. We aren’t doing this alone but rather through collaborations with local partners so we may ultimately restore them to areas where they once thrived.

Through a Wisconsin Coastal Management grant, we have partnered with Sheboygan County, Stantec, The Chicago Botanic Garden, and the Minnesota Landscape Arboretum to setup long-term monitoring locations in coastal counties, propagate hundreds of individuals, and raise said individuals in a shadehouse until they are vigorous enough for out-planting. Partners outside of this two-year grant include The Smithsonian Institute, North American Orchid Conservation Center, The Ridges Sanctuary, and Illinois College.  

Certain fungal communities work with orchid species through symbiotic relationships. In this way, the fungus is a surrogate root system for germinating seeds. Recognizing the importance of these relationships when returning a species to the landscape, our partner Illinois College is isolating unique fungal species associated with native orchids.

“It’s wonderful to see so many passionate researchers working together for the good of these species,” said Land Manger Matt Smith, “Through collaboration we can not only ensure the health of these species on our land, but in our region as well.”

In spring 2019, we will construct an Orchid Shade House, a nursery to raise native orchid seedlings for our immediate acreage and other natural areas that are suitable for temperate orchid reintroduction. We’re seeking the help of Citizen Science volunteers to document the health of orchid populations across our study sites, as well as anyone who has an interest in growing plants in the shade house. Through this project, you can help us discover the complex interconnected lives of Wisconsin plants and foster flowers that will be found by the next generation of explorers.

Bug o’the Week – Contemplating Insect Eggs

Greetings, BugFans,

Most insects begin their lives inside an egg that’s been deposited near/onto/into the correct food source, in the correct habitat for the eventual young.  The BugLady often photographs these eggs, but she didn’t know much about them.  Here are some Selected Short Subjects about insect eggs (and the BugLady apologizes in advance, she couldn’t help herself).

  • Insect eggs come in all sizes and shapes and colors (and some change colors between the time they are deposited and the time they hatch).  For some eggsquisite pictures, see http://www.atlasobscura.com/articles/the-blobby-dazzling-world-of-insect-eggs (ignore the text, which has a major eggsample of a “publish-in-haste-and-repent-at-leisure” boo-boo).  Some eggs are laid alone, some in clusters, and some en masse, enclosed in a webby or gelatinous protective case.  In some species, females detect pheromones left by recent, egg-laying females that tell them “This space is taken.”
eggs11 5rz
eggs cupplant13 14rz
egg11 1rz

  • Like an onion, an insect egg is layered, the layers manufactured within the female’s reproductive system via a process called oogenesis.  In general, the outer layer/egg shell/chorion is made of lipo-proteins, sometimes covered with a waxy coat.  The chorion may be sticky initially, so it will adhere to the surface it’s placed on.  There are several layers between the chorion and the inner layer, which is called the cell wall or vitelline membrane and which wraps the nucleus and yolk.  The surface of the shell has one or more tiny openings called micropyles, usually located on the top of the egg, and it may be minutely textured.
egg case zelus13 1rz
  • The egg that is manufactured within the female contains at its core an unfertilized female gamete/germ cell.  Fertilization happens when sperm find their way through one of the micropyles/micropylar canals after the egg shell is formed around the nucleus.  After fertilization, division of cells in the nucleus will result in an insect embryo that eats the yolk particles.
  • Seems like a lot of fuss – what’s the advantage of this system?  Only that developing a weatherproof egg allowed insect ancestors to emerge from life in the sea about 400 million years ago, that’s all (although aquatic insects still lay their eggs in water – more about that in a sec).  An inner membrane called the serosa restricts water flow through the egg shell; holding inside the moisture that Mom put there so her little bug wouldn’t desiccate, and keeping eggscess water outside.  This has allowed insects to eggspand into almost all environments.  Silverfish and a few groups of flies don’t have a serosa, but they lay their eggs in moist habitats, and their embryos develop really fast.
egg mlkweed12 1
  • Too much of a good thing?  Turns out that the qualities that allow the egg shell to protect the developing bug from drying out and from getting squished and (with varying success) from predation are not quite so good for oxygen eggschange.  The answer – more “pyles” or pores.  Though some air can be absorbed through the shell itself, the main ingress area(s) is/are other pore(s) called aeropyles. (older references say that the micropyle also allows oxygen to enter; others differentiate and use the term “aeropyle” for pores involved in gas exchange).  The number and arrangement of these pores depends on the species.
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  • Insect eggs face big swings in air temperature, and although embryos have higher metabolisms at higher temperatures (needing more oxygen), the rate of diffusion of oxygen through the chorion doesn’t necessarily keep up.  This can result in low oxygen concentrations (hypoxia) within the egg (one source said that the hatching of common green darner eggs is triggered by hypoxia).  In the recent BOTW about millipedes, the BugLady mentioned that arthropods were bigger 400 million years ago, when temperatures were cooler and atmospheric oxygen concentrations were higher.  Information about the interseggtion of temperature, metabolism, and oxygen diffusion through the chorion suggests that arthropod eggs may also have been super-sized.
  • How about aquatic insects that still lay their eggs under water?  Blogger Dragonfly Woman, an eggspert on giant water bugs in the family Belostomatidae, tells us that “Many aquatic insect eggs don’t have aeropyles at all and depend on oxygen flowing directly through the shell.”  She continues “[Abedus herberti eggs] have a structure called a plastron network.  Plastron networks are meshworks made up of many tiny projections of the chorion.  This meshwork is thought to trap air against eggs when they are underwater so that they don’t drown.  Many terrestrial eggs have these plastron networks and this structure may allow them to survive accidental submersion for some time.  Water bugs also usually have plastron networks that may be responsible for their survival while they are underwater. Lots of other aquatic insects that lay their eggs in water don’t have these structures at all.”  Read her full eggsplaination at https://thedragonflywoman.com/2011/02/07/the-anatomy-of-insect-eggs/.  Amazing pictures.
  • How long does it take for an egg to hatch?  Anywhere from a few days to months.  Many months, in the case of insects that overwinter in the egg stage.
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  • Eggs, it seems, don’t move, so they’re sitting ducks for predators.  Like their parents, many eggs are chemically protected against egg grazers and egg parasites.  The operative chemicals may be manufactured by Mom, or she may sequester them from plants that she eats (or both) before incorporating them into the shell.  Though direct paternal care of eggs is rare in insects, males of some species gift the female with toxic chemicals during courtship, and these are built into the egg.  Her eggs may have a toxic shell, be decorated with toxic hairs, be disguised with camouflage colors or brilliant with aposematic colors, or be unpalatable because of a layer of eggscrement.  In the “Very Cool” department, a female (herbivorous) stinkbug dots the outside surface of each of egg with feces that contain bacteria needed by her offspring to digest plant materials.  The newly-hatched bugs hang around the egg mass for a while, ingesting the bacteria.
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  • Honeybees are the only insects that incubate their eggs and young (by using body heat to keep the temperature in the nursery between 92 and 97 degrees) (they flap their wings like crazy).  Other insects are at the mercy of the temperature of air or water around them.  Warmer surroundings = faster hatching.
  • What do the plants think of all this?  Most than you’d eggspect.  The BugLady recalls the days when living things were divided firmly into two Kingdoms, Plant and Animal (eggcept for some pesky flagellated, unicellular, chlorophyll-bearing organisms lurking uneasily in between).  Plants were defined as organisms that didn’t move and didn’t have a sensory system and that produced their own food.  More and more studies show that plants not only receive signals, but they also communicate with other plants chemically (great Ray Bradbury short story about a man who designs a machine that lets him hear plants).  Research shows that plants recognize, react to, and communicate with plants downwind about grazing by caterpillars like gypsy moths, and that tomato plants are aware of oviposition by a moth and mobilize defensive proteins in their leaves before the caterpillars even hatch.
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Gypsy moth egg case

Write researchers Kim Jimwon et al, “Thus far, plants appear to recognize at least three events as indicators of future herbivory. First, some plants increase resistance against insects when a neighboring plant suffers insect herbivory. In this case, plants appear to “eavesdrop” on volatile organic compounds released by the neighboring plant under herbivory and elicit their defenses. Moreover, the volatile-receiving plants showed priming of defenses, meaning the receiver plants activated faster or stronger defenses upon the anticipated herbivory. Second, insect footsteps can induce defensive responses in plants…. Third, oviposition, one of the most common events preceding insect larval herbivory, can induce a variety of direct and indirect defenses of plants.”http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0037420.   For more about plant “senses”, see https://www.pri.org/stories/2014-01-09/new-research-plant-intelligence-may-forever-change-how-you-think-about-plants.  And, of course, in the eggscalating chemical battle, a few insects can secrete chemicals that moderate the plant’s anti-herbivore tactics.  The BugLady’s head may eggsplode.

After last week’s episode on Common green darners, BugFan Linda, whose eggstraordinary videos of pond life were featured in a January BOTW, responded that she had posted this video just a few days before https://www.youtube.com/watch?v=SgsEMAKUeX8.  AWESOME, Linda, thanks!

Kate Redmond, The BugLady

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