A different stink bug on the move in the kitchen: four-humped stink bug, Brochymena quadripustulata

 

Stink bugs like this four-humped stink bug may enter homes with firewood.

 

To differentiate four-humped stink bugs (left) from brown marmorated stink bugs (insert right) look at the shoulders. Four-humped stink bugs have spiny shoulders while shoulders of brown marmorated stink bugs lack spines.

In a previous episode we visited a domestic invasion by the nefarious brown marmorated stink bugs. This winter a different six-legged stinker has graced my kitchen, where something seems magical about the kitchen counter. On a chilly morning a few weeks ago, I was greeted by another member of the stink bug clan prancing across the kitchen counter, the four-humped stink bug which also goes by the name of rough stink bug. No, four-humped does not refer to some strange mating behavior nor does rough allude to rude conduct in polite company. These common names refer to some Bactrian camel-like adornments on the back of the stink bug and rows of spines at the margins of its “shoulders” just behind the head. Four-humped stink bugs are predominately arboreal, dining on a wide variety of trees, shrubs and vines from more than a dozen plant families. Apparently, sometimes they stray from the vegan plan and snack on juicy caterpillars. Who wouldn’t? In addition to my kitchen, they range throughout much of North America and are found in Central America, Africa, and Oceania according to Wikipedia.

Back to the mystery of why Mister Four-humped wound up in my kitchen. Scientists have discovered that in the more natural world, Brochymena spends the winter nestled beneath the bark of trees much like its cousin the brown marmorated stink bug. Not too many dead standing trees occupy my home, but frigid temperatures and a dead furnace recently necessitated a steady stream of firewood entering the house to be combusted in an attempt to keep the pipes and family from freezing. While gathering wood the other day, my spouse turned over a bolt of firewood and snuggled between two logs was a pair of four-humped stink bugs. Apparently, a stack of firewood is a suitable location to spend the winter if you are a stink bug. No doubt during this unusually chilly January and early February many stink bugs hitched a fatal ride into the woodbin and ultimately joined their kin in the afterlife following a toasty visit to the fireplace. For the lucky stink bug that awoke from its winter torpor and sidled across the counter, well it was just like Cooper Kupp going to Disney after the winning the Superbowl. The stink bug won a reprieve. As I placed it beneath a log in my neighbor’s abandoned woodpile, I thought I saw the bug smile. But hey, stink bugs have sucking mouthparts and no lips so it could not have smiled, just my imagination, right?         

Stink bugs often wind up inside homes in winter. Three years ago, I discovered a brown marmorated stink bug on my coffee cup early one morning. They are well-known home invaders. Recently, a four-humped stink bug raced across my kitchen counter. Discovering other four-humped stink bugs nestled in my firewood cache outside likely explains how they ultimately appear inside.

To learn how to distinguish other stink bugs in the home or outdoors from brown marmorated stink bugs, please visit the following link at the fantastic ‘Stop BMSB’ website: https://www.stopbmsb.org/stink-bug-basics/look-alike-insects/

Acknowledgements

A detailed account of the biology of the four-humped stink bug entitled “Life History and Laboratory Rearing of Brochymena quadripustulata with Descriptions of Immature Stages and Additional Notes on Brochymena arborea (Hemiptera: Pentatomidae)” by J. P. Cuda and J. E. McPherson was consulted for this episode.

From the Bug of the Week mailbag: World’s largest walking stick visits the Goddard Space Flight Center, Northern walkingstick, Diapheromera fermorata

 

A very large walkingstick appears to rest on the wall of a NASA building at the Goddard Space Flight Center near Washington, D.C. Image credit: Larry Coy

 

In October of 2008, The Natural History Museum of London headlined the discovery of the world’s longest insect, Phobaeticus chani, a giant stick insect from the rainforest of Borneo. This behemoth checked in at 22 inches in length and displaced the former record holder from Indonesia, Phobaeticus serratipes, another giant at 14 inches. Recently, Bug of the Week received a remarkable image of a walkingstick that make these gargantuans pale in comparison. The northern walkingstick in our feature image is at least 40 feet long. Yikes! Well, the clever photographer who took this crazy image assured me the camera magic that captured both the walking stick on a nearby window and the reflection of the NASA building behind him was not a trick of post-production. Whew, what a relief, but humans were never really in danger of being attacked by giant walkingsticks. They are vegetarians.

Walkingsticks are also known as stick insects or leaf insects in various parts of the world. Our local walkingsticks, northern walkingsticks like the one in our image, don’t quite measure up to those Asian giants, but at almost four inches these rascals are among the longest insects found in Maryland. They make their living eating foliage of trees and shrubs. In some years they are quite abundant and actually defoliate patches of trees, especially along rocky ridgetops.  Although lacking the tough armor of beetles and evasive flight of butterflies, they have perfected the art of crypsis, that is, they have an uncanny resemblance to features of their environment. This ruse of looking like branches of the trees on which they feed helps them avoid detection by hungry predators.

Many phasmids rely on crypsis, the art of looking like a plant part such as a dead leaf or a twig, to escape the hungry eyes of predators. Giant Australian stick insects and Malaysian leaf insects look like dead or living leaves, respectively, while the large Vietnamese stick insects and Costa Rican stick insects look like, well, sticks! Other phasmids like the Floridian two-striped walkingstick and Chilean chinchimolle emit noxious chemicals from glands behind their head to deliver a nasty surprise to nosy predators.

In addition to having greatly elongated body regions and appendages matching the colors and textures of twigs, walkingsticks move and pose in ways designed to fool sharp-eyed predators. As walkingsticks search for leaves, they sway slowly back and forth, mimicking the movement of a branch in the breeze. When not feeding or actively moving about, they assume a branch-like position with the front pair of legs extended directly forward. Their ability to hold an unflinching pose for hours is the envy of every mime. Unlike many adult insects, northern walkingstick insects never develop wings and nymphs and adults are quite similar in appearance. Some species of stick insects lay eggs on plants while others simply deposit them on the ground. For the northern walkingstick, winter is spent in the egg stage. A southern cousin of northern walkingstick, the two-striped walkingstick, is the longest insect in the United States and measures about half a foot. When camouflage fails to fool a hungry predator, walkingsticks may have another trick up their twig. Some species, including two-striped walkingsticks and elegant phasmatids, a.k.a. Chilean chinchimolles we met in previous episodes, have evolved glands on their thorax that emit foul-smelling, irritating chemicals to foil attacks by their enemies.

Acknowledgements

Bug of the Week thanks Larry Coy for providing the remarkable image of the northern walking stick featured in this episode. We also thank Dr. Audrey Grez of the University of Chile for identifying the chinchemolle. The following references were used in preparation of this episode: “4-Methyl-1-hepten-3-one, the Defensive Compound from Agathemera elegans (Philippi) (Phasmatidae) Insecta” by Guillermo Schmeda-Hirschmann, and “Defensive spray of a phasmid insect” by Thomas Eisner. Dr. Shrewsbury boldly modeled the rather large walking stick hair accessory in the Costa Rican rainforest.

Centaurea acaulis, Stemless Star-thistle | Catalogue of Organisms

In an earlier post, I commented on the diversity of species of the star-thistle genus Centaurea. Among the many, many species that have been assigned to this genus is the stemless star-thistle Centaurea acaulis* of northern Africa.

*Though dissolution of the polyphyletic Centaurea may lead to this species changing places. Banfi et al. (2005) listed it under the name of Colymbada acaulis.

Patch of stemless star-thistles Centaurea acaulis, from L'herbiel de Gabriel.

Centaurea acaulis is an inhabitant of dry, rocky habitats that is native to Tunisia and northeastern Algeria. As indicated by both the vernacular and botanical names, its growth habit lacks a central stem. Instead, the long, lobed leaves (which can be up to about a foot in length going by photos provided by Agut Escrig et al., 2021) lie prostrate on the ground. These leaves end in a large, ovate apical section with lobes running down the side of the central rib, becoming smaller towards the base. Flower heads are solitary and carry a mass of bright yellow florets. The involucral bracts (the 'scales' around the outside of the base of the flower head) are flat and green with darker longitudinal veins. The distal section of the bracts is triangular with a membranous, ciliate margin and typically (though not always) ends in a long spine. A closely related species found in northwestern Algeria and Morocco, C. oranensis, has historically been treated as a subspecies of C. acaulis (under the name C. acaulis ssp. boissieri, because botanical nomenclature is weird). However, C. oranensis was raised to species level by Greuter & Aghababian (in Greuter & von Raab-Straube, 2005) on the basis of its distinct involucral bracts, which are distally blackish, ovate and concave, with a margin of dense, long, stiff setae.

Recent years have seen this species extending its range northwards with populations now found in Spain, Italy and Malta. In Malta, it was initially found grown in a disturbed area with particularly alkaline soil (Buttigieg & Lanfranco 2001). The mechanism of its arrival is uncertain. It could have dispersed naturally across the Mediterranean, or it may have arrived mixed into bird seed. However it got there, one might expect that as the south of Europe becomes increasingly hotter and drier, the stemless star-thistle will continue to spread.

REFERENCES

Agut Escrig, A., J. P. Solís Parejo & P. Urrutia Uriarte. 2021. Noticias sobre la presencia de Centaurea acaulis L. (Asteraceae) en la Península Ibérica. Flora Montiberica 81: 51–54.

Banfi, E., G. Galasso & A. Soldano. 2005. Notes on systematics and taxonomy for the Italian vascular flora. 1. Atti Soc. It. Sci. Nat. Museo Civ. Stor. Nat. Milano 146 (2): 219–244.

Buttigieg, R., & E. Lanfranco. 2001. New records for the Maltese flora: Centaurea acaulis L. (family: Asteraceae). Central Mediterranean Naturalist 3 (3): 147–148.

Greuter, W., & E. von Raab-Straube (eds) 2005. Euro+Med notulae, 1. Willdenowia 35: 223–239.

Lifestyles of the Rosalinidae | Catalogue of Organisms

Among the modern foraminiferans, one of the most prominent radiations is among members of the Rotaliida, characterised by globose chambers and calcareous, hyaline test walls. Among the numerous families making up the Rotaliida are members of the Rosalinidae.

Benthic form of Rosalina globularis, from Brady (1884).

Rosalinids may be regarded as fairly typical-looking marine rotaliids with the test growing freely as a low trochospire (so a flattened cone or dish shape). The aperture of the test is a low slit on the interior margin along the umbilicus (Hansen & Revets 1992). Rosalinids have a complex life cycle involving both benthic and planktonic stages (Sliter 1965). The asexually reproducing diploid stage is benthic. Depending on conditions, diploid individuals may divide to produce other diploid individuals, resulting in several asexual generations. Eventually, however, the diploid generation will undergo meiosis to produce the haploid sexual generation (in the common species Rosalina globularis, this is induced by exposure to warmer water). In the sexual generation, a large globular chamber forms at maturity that covers the umbilical side of the test. This float chamber becomes filled with gas, allowing the foram to disperse planktonically before releasing gametes to produce the next diploid generation. Planktonic individuals are distinct enough in appearance from their benthic counterparts that they were long mistaken for distinct taxa before their identity was revealed by lab cultures.

Life cycle of Rosalina globularis, from Sliter (1965).

The majority of forams are particulate feeders. A network of filamentous pseudopodia radiating outwards from the cell body captures micro-organisms and other organic particles. However, one genus of rosalinids, Hyrrokkin, lives as parasites on sessile invertebrates (Cedhagen 1994). Species of this genus have variously been found on sponges, corals and bivalves. On sponges, they settle on the inhalent surface of the sponge and dissolve the underlying tissues. On bivalves, they form pits on the shell surface from which they bore holes through to the body cavity. Pseudopodia extended through this hole allow the foram to feed on host tissue. Infested hosts may bear multiple scars from the foram moving about on the outer surface. The forams may also feed on other animals such as polychaete worms or bryozoans attached to the surface of their primary host. In such cases, Hyrrokkin remains in its original pit but develops an irregularly shaped chamber with its aperture directed towards the alternate prey. Hyrrokkin species evidently do well from their rapacious lifestyle: whereas other rosalinids are only a fraction of a millimetre in diameter, Hyrrokkin sarcophaga is an absolute giant reaching around six millimetres across and with protoplasm containing thousands of nuclei. Proving once again that one may make a great deal of profit from the labour of others.

Cross-section of Hyrrokkin sarcophaga boring into shell of file clam Acesta excavata, from Schleinkofer et al. (2021).

REFERENCES

Cedhagen, T. 1994. Taxonomy and biology of Hyrrokkin sarcophaga gen. et sp. n., a parasitic foraminiferan (Rosalinidae). Sarsia 79: 65–82.

Hansen, H. J., & S. A. Revets. 1992. A revision and reclassification of the Discorbidae, Rosalinidae, and Rotaliidae. Journal of Foraminiferal Research 22 (2): 166–180.

Sliter, W. V. 1965. Laboratory experiments on the life cycle and ecologic controls of Rosalina globularis d'Orbigny. Journal of Protozoology 12 (2): 210–215.

Colus and Co. | Catalogue of Organisms

The neogastropods have long been a challenge taxonomically. They are extremely diverse, encompassing a large number of species with a wide range of lifestyles, but they also exhibit exhibit regular patterns of convergence and/or conservatism between different lineages. Perhaps the most challenging group of all has been the whelks, commonly recognised as the superfamily Buccinoidea, a massive radiation of over 3300 known species. Whelks are particularly diverse in colder regions of the world's oceans, including amongst their number there the members of the family Colidae.

Hairy colus Colus pubescens, copyright E. A. Lazo-Wasem.

Colus has been used as the basis of a family group name at many levels of whelk classification, whether it be Colidae, Colinae or Colini. The gastropod classification laid out by Bouchet et al. (2017) recognised 'Colini' as a diverse tribe within the main whelk family Buccinidae, including a range of cold-water taxa. However, a more recent phylogenetic analysis of the buccinoids by Kantor et al. (2021) found Bouchet et al.'s concept of Colini to be polyphyletic, placing the type genus Colus outside what the called the 'core Buccinoidea'. As such, they raised Colidae to the status of a separate family and restricted it to just two genera, Colus and Turrisipho.

In this restricted form, the Colidae are thin-shelled, medium-sized to large whelks with the largest having shells up to twenty centimetres in length. The shells are fusiform to ovate in shape with a more or less elongate siphonal canal and covered by a brown periostracum. Axial sculpture is absent; spiral sculpture is expressed as more or less prominent cords. The aperture is closed with a operculum bearing a terminal nucleus. The animal has a more or less long proboscis. The radula bears three teeth per row; the middle tooth has a more or less square base and one to three cusps, with the middle cusp the largest, whereas the lateral teeth bear three hooked cusps with the outermost cusp significantly larger than the other two. None of these features, it should be noted, is entirely unique to the Colidae (Kantor et al. 2021).

Turrisipho dalli, from BoldSystems.

Members of the Colidae are found in the Arctic and northern Atlantic Oceans, from subtidal to bathyal depths. Because they are not targeted commercially, the life habits of colids have not been well studied. However, what we do know indicates that they are likely predators on other invertebrates (Kosyan 2007). The long proboscis of most species is probably used to pull infaunal animals such as amphipods and bivalves out of their burrows. Colids have well-developed salivary glands and it is possible that these may produce toxins as found in other neogastropods. They do not have anything like the elaborate venom delivery setups like those found in the conoids, but even a little dose of toxic saliva helps to subdue a struggling crustacean.

REFERENCES

Bouchet, P., J.-P. Rocroi, B. Hausdorf, A. Kaim, Y. Kano, A. Nützel, P. Parkhaev, M. Schrödl & E. E. Strong. 2017. Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia 61 (1–2): 1–526.

Kantor, Y. I., A. E. Fedosov, A. R. Kosyan, N. Puillandre, P. A. Sorokin, Y. Kano, R. Clark & P. Bouchet. In press 2021. Molecular phylogeny and revised classification of the Buccinoidea (Neogastropoda). Zoological Journal of the Linnean Society.

Kosyan, A. R. 2007. Morphological features, ecology, and distribution of poorly studied molluscan genera of the Colinae subfamily (Gastropoda, Buccinidae) from the far eastern seas of Russia. Oceanology 47 (4): 531–536.

Destinations: Piedras Blancas National Park, Costa Rica and a backyard in Columbia, Maryland: Sand wasps – Crabronidae

 

Last summer a four-lined-stink bug hunter prepared to dig a burrow in the ground where a sand box once rested.

 

Last week we braved frigid temperatures in Maryland to visit larvae of a really cool beetle, the eyed elater, chillin’out beneath the bark of an oak tree, brrr. So, let’s warm up and start this week’s adventure on a sunny beach in Costa Rica where we meet fascinating sand wasps. Sand wasps belong to a family of predatory wasps known as crabronids. After excavating burrows in the sand in which to raise their offspring, female wasps hunt other insects that serve as food for their young. Some, including those in the genus Stictia, have colorful common names like “horse guard" and "insecto policia". These agile fliers often frequent farms where they capture horse flies as they hover and land on horses and other livestock. Stictia sand wasps deliver a paralyzing sting to their victim, transport the fly back to their sandy burrow, and stuff them into a subterranean crypt. Their victims are consumed by wasp larvae that hatch from eggs deposited by female flies. After provisioning the burrow with a full complement of paralyzed prey for her offspring, the wasp will close the burrow with sand. She may add debris from the surrounding area to camouflage the nest. You see, sand wasps have their own complement of enemies including ants that raid sand wasp nests and devour the young within.

On a sunny beach in Costa Rica burrowing arthropods are busy. A ghost crab disappears into its subterranean refuge. Above the high tide line, a crabronid wasp prepares its burrow to receive paralyzed prey which serve as food for its young as they develop beneath the sand. On a warm day in July in a sandy yard in Maryland, a stink bug hunter quickly disappears beneath the sand as she readies the nest for her young.

Keeping with our wistful reverie of warmer times to come, we stop by a sandy backyard in Maryland on a warm summer’s day to meet another sand wasp. This little beauty, Bicyrtes quadrifasciatus, is sometimes called the four-lined-stink bug hunter due to its propensity to capture stink bugs and other members of the true bug clan (Hemiptera) that serve as food for its young. Although I did not have the opportunity to witness a hunting victory of the four-lined-stink bug hunter, several researchers and naturalists have seen this clever tracker provisioning their burrows with nymphs of the noxious brown marmorated stink bug (BMSB). Sand wasps join a cabal of other beneficial predators, including assassin bugs, spiders, and mantids we met in previous episodes contributing to the demise of BMSB in our region. Way to go wasps!    

Acknowledgements

Two interesting articles, “Survey of Native Biocontrol Agents of the Brown Marmorated Stink Bug in Pennsylvania Fruit Orchards and Adjacent Habitat” by David Biddinger, John Tooker, Alex Surcica, and Greg Krawczyk, and “Nesting Behavior of the Sand Wasp Stictia maculata (Hymenoptera: Sphecidae) in Costa Rica” by Robert Matthews, Richard Saunders and Janice Matthews, were consulted in preparing this episode.