Hibiscus Scentless Plant Bug Life Cycle

It is a rare occasion when I am able to document all life stages of an insect species, let alone in the same location, or over a period of a couple of days. That is what happened, though, when I photographed a population of a scentless plant bug, Niesthrea louisianica, sometimes called the Hibiscus Scentless Plant Bug. Indeed, hibiscus and related plants in the family Malvaceae are their hosts. Our saga takes place in Okawville, Illinois, USA, in October of 2023.

While exploring the yard at my sister-in-law's home, I happened to notice adults and nymphs of this insect on buds of what I learned later was the plant known as Rose-of-Sharon, Hibiscus syriacus. Even the adults are not very large, measuring only 6.5-8.5 millimeters in body length. They are noticeable because they are so brilliantly colored in orange and red, with legs annulated (banded) in black and white. Niesthrea louisianica is a mostly southern U.S. species, but ranges from New York to Florida, and west to Iowa, Texas, Arizona, Utah, and California.

Apparently it is not unusual to find all stages in the life cycle at the end of the plant's growing season, and the adult insects overwinter anyway. Females can live about two months, males roughly fifty days. There can be at least three or four generations per year in southern latitudes, fewer farther north. Females deposit eggs in small batches, up to 36 in number, on the underside of leaves, beneath the bracts of the flower buds, or on the seed heads. One female can lay up to seven hundred eggs in her lifetime. I spotted a couple of egg clusters, one being guarded, presumably by the female that laid them.

The first instar nymphs that emerge from the eggs are so tiny! This species goes through five instars, an instar being the interval between molts. Like all true bugs, metamorphosis is "simple," each instar incrementally larger than the last, with the final molt to adulthood resulting, in this case, in a winged, sexually-mature individual. All life stages feed on the flower buds and seeds of the host plant, inserting the stylets of their rostrum to reach the interior fluids and tissues.

The activity period of the Hibiscus Scentless Plant Bug differs with latitude, but the life cycle begins in April or May, when the overwintered females lay eggs. It concludes with the end of the growing season, in October or even later.

One interesting aspect of Niesthrea louisianica is its potential role in controlling a problematic plant called Velvetleaf, Abutilon theophrasti. The bugs can carry pathogenic fungi in the genera Fusarium and Alternaria, which ride on the insects and infect the seeds of the plant, weakened from the feeding activities of the insect.

The "scentless plant bug" moniker may not apply in the case of the Hibiscus Scentless Plant Bug. They possess metathoracic glands, and a single dorsal abdominal gland, that produce copious amounts of exocrine chemicals for self-defense. Not that this deters spiders, one of their chief enemies, nor does it prevent parasitoid tachind flies, genus Leucostoma, from attacking the adult bugs. Scelionid wasps, genus Telenomus, exact a toll as parasitoids of the bug's eggs.

This is one of those species that fits the entomological addage of "Once you see one, you will see them everywhere." They are "locally abundant," like many host-specific phytophagous (plant-feeding) insects. They will not be on every plant because the defensive chemicals of the host plant vary from one individual plant to the next. Be on the lookout for them in Ohio, Indiana, and northern states currently out of their accepted range. Climate change may be driving a northerly range expansion.

A pair of less colorful specimens from Cape May, New Jersey, September, 2017

Sources:Baker, James. 2016. "Hibiscus Scentless Plant Bug," NC State Extension Publications
Kremer, Robert J. 1992. "Integration of a Seed-feeding Insect and Fungi for Management of Velvetleaf (Abutilon theophrasti) Seed Production," Proceedings of the Eighth Annual Symposium on Biological Control of Weeds.
Jones, Walker A., H.E. Walker, P.C. Quimby, and J.D. Ouzts. 1985. "Biology of Niesthrea louisianica (Hemiptera: Rhopalidae) on Selected Plants, and its Potential for Biocontrol of Velvetleaf Abutilon theophrasti (Malvaceae)," Annals of the Entomological Society of America 78(3): 326-330.
Slater, J.A., and R.M. Baranowski.1978. How to Know the True Bugs. Dubuque, Iowa: Wm. C. Brown Company Publishers. 256 pp.
Moorehouse, Angella. 2023. Flower Bugs: A Guide to Flower-associated True Bugs of the Midwest. Minnetonka, Minnesota: Pollination Press, LLC. 360 pp.
Steill, Jennifer, and Jason Meyer. 2003. The Rhopalidae of Florida "Scentless Plant Bugs." Insect Classification Project. 23 pp.

A group of juveniles on an unidentified host plant, New Jersey

Book Review: Underbug

Termites exist at the intersection of biology, chemistry, ecology, engineering, and perhaps even philosophy. In Underbug: An Obsessive Tale of Termites and Technology, author Lisa Margonelli masterfully weaves all of these elements together, and then some. She manages to remain in that sweet spot between total participation in the story, and complete detachment, never overtaking the spotlight of her subjects, both insectian and human, but still revealing the personal impacts of where her investigations took her. She maintains empathy with the reader while taking them on a globe-trotting journey.

Underbug has more to say about humanity than you would expect in a book ostensibly about insects, let alone insects we consider economic pests. This is about where curiosity and imagination can take you. It ventures from the microscopic world of termite gut fauna to the megascopic, landscape-writing engineering of millions of diminutive members of a termite colony. How are they so successful? How can we harness their power to digest cellulose and use it to manufacture “grassoline?” What lessons exist for how to reclaim an abandoned mine and turn it back to its native grandeur?

It may be cliché to say that a book has something for everyone, but this one truly does, provided you are prone to a fascination with science, or relish contemplating the planet and our own place on it.

The book is divided into six parts, each one set off by a black-and-white illustration that gives the impression, appropriately, of a woodcut print (they are linoleum block prints by Thomas Shahan). The dust jacket has intentional holes in it, as if the book has already been “digested” by its very subject. How perfect. Margonelli manages to have a reverence for both termites and science, but never comes off as preaching or dogmatic. There is humor here and there, and the prose are descriptive enough to put you right in the center of things.

As a failed academic myself, I felt overwhelmed occasionally by the mathematics, genetics, and technological aspects of the stories (there are several), but remained captivated by the human characters and, of course, the mysteries of the insects.

Margonelli ultimately questions the accepted scientific course of the abstraction of natural processes, whether it has its limits, or if it is even a potential failing of our own species. Are we too attached to the idea that every other species, every habitat, serve us first, to justify its existence?

Without giving too much away, the conclusions reached are, as one might expect, inconclusive; for termites exist at the intersection of the known, the unknown, and the unknowable. Sometimes the biggest question for a researcher or engineer is when to give up.

Underbug was published in 2018, by Scientific American / Farrar, Straus and Giroux, New York. It is 303 pages, including notes and index. This is as much an adventure book as it is a revealing glimpse into what defines science in the twenty-first century. Highly recommended.

Book Review: Flower Bugs

I must preface this review by stating that the author, Angella Moorehouse, and publisher, Heather Holm, are personal friends. That is not why I am conflicted in my reaction to this book. Neither is it because I view this book as being in competition with any of my own works. We cannot have enough literature devoted to promoting public understanding and appreciation of insects. It boils down in part to my own biases and expectations. With that, you will still receive an honest appraisal.

Pollination Press, LLC produces plant-based books about insects, usually restricted to a particular geographic region. Holm's comfort zone is clearly in botany, though her prior books about bees and wasps, as they relate to flowering plants, demonstrate a command of general entomological knowledge, and dedication to thorough research. There is no question that her books deliver accurate, factual information. From my perspective, as an entomologist with little familiarity or interest in plants, I immediately see what is "missing" in terms of species, even families, because those insects are not associated with forbs.

There is a desperate need for more books that illustrate the ecological networks of different organisms, but Flower Bugs: A Guide to Flower-Associated True Bugs of the Midwest is limited to the flowers of herbaceous flowering plants, and almost exclusively those true bugs that may play a role in pollination, or those species that frequent flowers as a place to ambush other pollinators. The territory covered is eight states (Illinois, Minnesota, Wisconsin, Iowa, Missouri, Michigan, Indian, and Ohio), and adjacent southern Ontario, Canada. The book is in fact based mostly on a detailed survey of locations in western and central Illinois, over a period of seven years.

The true bugs treated are further restricted to the suborder Heteroptera, which includes the larger, more obvious examples like stink bugs, assassin bugs, mirid plant bugs, and seed bugs, but leaves out the families of aquatic bugs, plus the other two suborders that include cicadas, leafhoppers, spittlebugs, and aphids. All of these specifics are stated explicitly in the introduction of the book.

The layout of Flower Bugs includes the trademark features of Pollination Press' other books: prolific and quality imagery, geographic range maps, seasonal distribution bars showing what months the adult insect is present, tables of plant species associated with each insect species addressed, diagrams of taxonomic relationships, a glossary, checklists, and a visual index.

The front matter of the book is, as usual for this press, presented to near perfection in degree of detail, and coverage of morphology and ecology. It is an excellent introduction to true bugs as a whole, for the intended audience of native plant gardeners, naturalists, resource management personnel, and others.

The species accounts cover the overall geographic range, variation in physical appearance, life cycle, feeding, habitat, and native plant associations. The images are occasionally redundant, but frequently include photos of the immature stages, which most field guides fail to do. In cases of the mirid plant bugs, assassin bugs, and other families for which there are few flower associates, there are photos of other species for comparison, and to better indicate the full diversity of these groups. Given the lack of any other contemporary guides to true bugs, this gesture is appreciated.

The last book to cover the true bugs for a popular audience was probably Bugs of the World, by George C. McGavin, published in 1993 and 1999 by Blandford, an imprint of Cassell, in London. Back then, the true bugs were classified much differently. In 1978, How to Know the True Bugs, by James A. Slater and Richard M. Baranowski, was published by Wm. C. Brown Company Publishers in Dubuque, Iowa, as part of their "Pictured Key Nature Series." That reference also covered the suborder Heteroptera, but assumed the user had a pinned specimen and a microscope at hand.

The fact that Flower Bugs is the most up-to-date popular reference to North American Heteroptera, no matter how limited the scope, is enough to recommend it. You will no doubt find yourself stalking the true bugs in your own yard, neighborhood park, or other favorite habitat. You can be confident that this book will provide you with an accurate ecological perspective, and interpretation of the behaviors of these insects.

Last Night to Blacklight?

A green mantisfly (left) and a leafhopper parade across the top of the sheet behind our blacklight at night.

Back on October 23, 2023, we had an abnormally warm day of 86℉. I took advantage of this to put out a blacklight, in front of a white sheet, on our back yard fence that night. Because of insect decline, and the role of light pollution in driving down the survival and reproductive rates of insects, I try and blacklight less frequently these days. Never mind that the federal penitentiary, located two blocks behind our house, is lit up like Las Vegas every night. I consider it something of a miracle that we are able to draw any insects to our dim illumination devices, but we get a surprising diversity. This night was no different, despite being so deep into autumn.

Japanese Maple Leafhopper

One wonderful aspect of putting out a blacklight at this time of year is that we are not inundated with huge numbers of caddisflies, as we often are, especially in late spring. Instead, fall is the season of true bugs (order Hemiptera), lacewings and their allies (Neuroptera), flies (Diptera), select late-season moths (Lepidoptera), and a few beetles (Coleoptera).

Trumpet Vine Moth

Indeed, during daylight hours in late October, the air is positively thick with aphids and tiny leafhoppers, and buzzing with the drone of larger bugs like stink bugs and leaf-footed bugs. Many of these true bugs overwinter as adults, and are seeking places to shelter through the cold months. Some species of aphids move to alternate hosts for the winter, and so have winged individuals for dispersal to those plants. It has been windy, though, and even wingless aphids have been blown everywhere. Our fence is crawling with them, even as I write this on November fourth.

Mirid plant bug, Hyaliodes sp.

Leafhoppers are among the most speciose of insects in our yard, as both resident insects and "fly-by" individuals for which we have no host plants to support them. Most of that diversity occurs under five millimeters in body length. A two- or three-millimeter leafhopper can still be surprisingly colorful, though.

Leafhopper, Erythridula sp.

Leafhopper, Norvellina helenae

Leafhopper, Gyponana sp.

Leafhopper, Gyponana gladia?

Red-banded Leafhopper, Graphocephala coccinea

Planthoppers representing several families were also present at our light, some a little bit worn.

Delphacid planthopper, Liburniella ornata

Northern Flatid Planthopper, Flatormenis proxima

Derbit planthopper, Otiocerus stolli

We had three different species of mantidflies, also known as mantispids, at the lights. They are predatory and readily stalk smaller insects drawn to our light source. Their more familiar kin, green lacewings and brown lacewings, were present, too. Green lacewings are frequently brown, or reddish, at this time of year, and also overwinter in the adult stage.

Mantidfly, Dicromantispa interrupta

Green Mantidfly, Zeugomantispa minuta

Mantidfly, Dicromantispa sayi

Green lacewing, Chrysoperla sp.

Flies are ever-present, with blow flies spending the winter as adults hidden under the siding of your house, and in other snug cavities. Syrphid flies were still visiting the aster flowers in our neighborhood during the day. What came to the light, however, were long-legged flies, tachinid flies, and pomace flies.

Marsh fly, Dictya sp.

Unidentified tachinid fly

Unidentified long-legged fly

Black scavenger fly, Sepsis sp.

Mating pair of leafminer flies, family Agromyzidae

Moths are what entomologists typically deploy blaclights for, and of course there were some of those, too. Some species appear only during the fall, and/or the winter, so it pays to keep the blacklights handy for the odd warm evenings. Owlet moths, geometer moths, and grass veneers are among the usual suspects, but look for much smaller moths, too.

Green Cutworm Moth, Anicla infecta

Ailanthus Webworm Moth, Atteva aurea

Corn Earworm Moth, Helicoverpa zea

Ipsilon Dart, Agrotis ipsilon

Juniper-twig Geometer, Patalene olyzonaria, I believe.

Grateful Midget, Elaphria grata

Oh, I almost forgot about barklice (order Psocodea). Three species showed up on October twenty-third, probably representing three different families. Barklice are easily mistaken for planthoppers, or even tiny moths, but they have chewing mouthparts instead of a beak or a proboscis.

Common barklouse, Indiopsocus sp.

Narrow barklouse, Graphopsocus cruciatus

Common barklouse, Trichadenotecnum alexanderae species complex

Beetles that showed up included several species of ground beetles (Carabidae), small dung beetles (Scarabaeidae), and lady beetles (Coccinellidae), along with representatives of less familiar families.

Vivid metallic grouond beetle, Chlaenius tricolor

Colorful foliage ground beetle, Lebia vittata

20-spotted Lady Beetle, Psyllobora vigintimaculata

Antlike flower beetle, Notoxus sp.

Silken fungus beetle, family Cryptophagidae.

More warm days are in the forecast for next week, so I may at least flip the front porch light on and check for insect guests. Even the vague warmth of the blacklight results in substantial carnage, with smaller, frail insects perishing from the heat, so that is another reason to use the apparatus sparingly. It is still a great tool, however, for evaluating insect variety and density. More on light pollution to come, in a later post.

Aphid, Drepanaphis sp.

Note: Here is the link to all of the arthropods observed on this date on iNaturalist.