The Nationals aren’t the only ones wearing red at Navy Yard: Get ready for red-shouldered bugs, Jadera haematoloma

 

By late summer, hordes of winged red-shouldered bugs and wingless nymphs will cluster on the bark of golden rain trees.

 

Lining a promenade in Navy Yard, this grove of golden rain trees serves dinner for legions of golden rain tree bugs.

On a rare 70-degree day two weeks ago, good fortune found me on a pleasant promenade that connects New Jersey Ave. and 4th Street south of the US Department of Transportation in Washington DC, a section of the city known as Navy Yard and which serves as the home of the Nationals baseball team. A beautiful water feature graces the promenade and this urban refuge is shaded by golden rain trees, Koelreuteria paniculata, beautiful ornamental trees widely planted in landscapes throughout North America and worldwide. These sturdy trees are favored in urban landscapes by virtue of their ability to withstand a variety of growing conditions and soil types. Their ornamental value comes from large clusters of bright yellow flowers displayed from summer into fall. In autumn the flowers produce interesting clusters of showy, papery seedpods. The seedpods are reddish-purple when developing and turn brown as they mature. Several ebony seeds are produced within each pod. Legions of seeds rain down to earth beneath the golden rain tree. Sturdy shells inhibit degradation of the pods in winter and a nutritional bounty remains in spring. 

Our southern and gulf-coast states are home to several native plants belonging to the golden rain tree family of plants, the Sapindaceae, commonly called soapberries. A striking insect called the red-shouldered bug, or golden rain tree bug, has evolved to use the seeds of soapberries as food. Golden rain tree bug is a “true” bug identified by its sucking mouthparts, young that are called nymphs, and half-leathery, half-membranous front wings. Jadera belongs to the clan of true bugs known as scentless plant bugs or Rhopalidae. We met other rhopalids in previous episodes including boxelder bugs and curious Niesthrea lousianica, the eater of mallows. Historically, red-shouldered bugs occupied neotropical realms in Central and South America, and in North America were found primarily in southern states including Florida, Texas, Arizona, and California, where they dined on native soapberries. 

On a promenade in Navy Yard, red-shouldered bugs scramble across the pavement and scale rain trees while playing the mating game. The guys seem to have a hard time keeping pace as females lead the way. Potential interlopers access their options and quickly move along. When it comes to dining, red-shouldered bugs are a chummy lot as they share meals of rain tree seeds.

Beneath golden rain trees, thousands of seeds produced last summer provide a ready food source for red-shouldered bugs this spring.

The introduction of golden rain tree to our country in the 1700s provided an excellent opportunity for the red-shouldered bug to try Asian cuisine. Golden rain tree is now one of the favored foods of this bug throughout our country. During the past century, red-shouldered bugs have made a steady march northward, discovered in North Carolina in 1938, Virginia in 1987, and Maryland in 2002. Scientists believe that milder winters associated with climate change facilitated the range expansion of red-shouldered bugs into regions where chilly winter temperatures previously excluded them. As I walked the golden rain tree promenade, dozens of red-shouldered black bugs milled about on the ground feasting on fallen seeds, scrambling up trees, and basking on sidewalks. While hordes of bugs were a source of delight for me, so many bugs in one place night unnerve other visitors to the Yard. 

Soon bright red nymphs of the golden rain tree bug will appear on the ground, sucking nutrients from seeds of rain trees.

As the weather turns warm, these red and black beauties will mate, lay eggs, and feed on the bounty of the rain tree. Using their beak, nymphs and adults pierce the tough seed coat and probe the nutritious meat of the seed. Digestive enzymes pumped through the beak into the seed break down proteins, fats, and carbohydrates. Once liquefied, these nutrients are sucked back up the beak and into the gut of the bug where they are converted to proteins used for growth and reproduction or broken down to supply the energy for all the running about and mating that occupies the time of these bugs. These bugs have been known to enter buildings in autumn when the weather finally turns cold and bugs seek shelter. In the wild, shelter might be a fallen log, a pile of branches and leaves, or a rocky outcropping. In their new urban home, winter shelter for the red-shouldered bug might be one of the many dining establishments or agency buildings found in Navy Yard. Will they appear in other venues, maybe in center field at Nats Park with humans wearing red? Probably not, but only time will tell.

Sometimes the simplest tasks, like transporting a soapberry, get complicated when you’re a bug.

 Acknowledgements

 We thank members of the Pick lab, Jackie, and Others Coffee for providing the inspiration for this episode of Bug of the Week. “Jadera haematoloma, Another Insect on its Way North (Heteroptera: Rhopalidae)” by Richard L. Hoffman and Warren E. Steiner, and “Specialization of Jadera Species (Hemiptera: Rhopalidae) on the Seeds of Sapindaceae (Sapindales), and Coevolutionary Responses of Defense and Attack” by Scott P. Carroll and Jenella Loye, were consulted in creating this episode.

Voley, Voley, Voley | Catalogue of Organisms

Over a third of all living mammal species are rodents. In cooler regions of the Northern Hemisphere, the rodent fauna is often dominated by the Microtinae, the group of mouse-like rodents including voles and lemmings. And in North America, the most widespread of all microtine species is the eastern meadow vole Microtus pennsylvanicus.

Eastern meadow vole Microtus pennsylvanicus, copyright Gilles Gonthier.

The eastern meadow vole is found over most of Canada and a large part of the northern and eastern United States, with the subspecies M. p. chihuahuensis known from Chihuahua in northern Mexico. This species is about the size of a small rat, being from 14 to 20 cm in length with about three to six centimentres of that length being tail (Reich 1981). They are generally yellowish-brown in colour with black tips on the hairs though individuals vary significantly in brightness and shade. Western populations are supposed to be lighter in coloration than eastern, and southern individuals tend to be larger than northern. As an indication of this species' variability, Reich (1981) recognised 28 recognised subspecies.

Eastern meadow voles are primarily inhabitants of grasslands, with a preference for damper habitats, though they may also be found in woodlands. They mostly live in burrows underground, emerging to the surface to forage for food. Eastern meadow voles are generalist feeders, browsing on most available forms of low vegetation: grasses, sedges and herbs. When populations reach their peak, they may cause significant damage to woody plants by ringbarking their trunks. Individuals may seemingly be active at just about any time of day.

Eastern meadow vole in a state of danger, copyright David Allen.

Like other small rodents, meadow voles are short-lived animals with estimates of average lifespan ranging from just two or three months to ten to fourteen months (Reich 1981). Studies of movement patterns indicate that mature females generally maintain distinct, non-overlapping ranges whereas males range further and with less concern for others (Madison 1980). Mating behaviour appears generally promiscuous: males will range over the territories of multiple females and litters with mixed paternity are not uncommon (Boonstra et al. 1993). Paternal behaviour has been observed among eastern meadow voles in laboratory populations but all indications are that wild males do not remain with females after mating. Males often bear wounds indicative of intra-species conflict. These may be the result of males fighting over access to females but Madison (1980) suggested a potential alternative. Less dominant males might be more likely to attempt to approach females earlier or later in their oestrus cycle as the females are more likely to be guarded by dominant males when at their peak. While avoiding attacks from their dominant brethren, these minor males might find themselves violently rebuffed by a female who is just not yet in the mood.

After mating, gestation lasts for about three weeks, usually resulting in a litter of four to six babies. Weaning then takes place after about two weeks. Females forage far less while lactating than at other times. It might seem counter-intuitive for a female to reduce feeding when her energy demands are presumably at their peak but again Madison (1980) suggests an explanation: perhaps her energy needs are such that she simply lacks the capacity for extensive wandering. Young may potentially remain with their mother for some time after weaning but eventually they will be forced out of the parental burrow, leaving to face the wide world on their own. And when you're the size of a vole, that's a very wide world indeed.

REFERENCES

Boonstra, R., X. Xia & L. Pavone. 1993. Mating system of the meadow vole, Microtus pennsylvanicus. Behavioral Ecology 4: 83–89.

Madison, D. M. 1980. Space use and social structure in meadow voles, Microtus pennsylvanicus. Behavioral Ecology and Sociobiology 7: 65–71.

Reich, L. M. 1981. Microtus pennsylvanicus. Mammalian Species 159: 1–8.

Anchor Sponges | Catalogue of Organisms

Sponges are, by their very nature, a challenging group taxonomically. At the macroscopic level, they are often amorphous and indeterminate in appearance. As one taxonomist complained in 1842 (as quoted in Hooper & Van Soest 2002): "there is so much that is in common to them, and each adapts itself so readily to circumstances and assumes a new mask, that it requires a tact, to be gained only by some experience, to recognize them under their guises; while we labour, perhaps in vain, to devise phrases which shall aptly portray to others the characteristics of objects that have no fixed shape, and whose distinctive peculiarities almost cheat the eye". Reliable identification typically requires the close examination of microscopic details, in particular the conformation and arrangement of the mineralised spicules that make up the skeleton of many sponges.

Myxilla incrustans, copyright B. E. Picton.

The Myxillidae are a family of marine sponges that, so far as we currently know, are most diverse in temperate and frigid waters. Like other members of the class Demospongiae, the most diverse of the recognised sponge classes, they have a skeleton of spicules constructed from silica. Different arrangements of spicules allow the body of the sponge to be divided into two layers. In the outer ectosoma, which can be thought of as the 'skin' of the sponge, elongate spicules are vertically radiating or placed in 'bouquet' arrangements with a palisade of vertical spicules surmounted by radiating clusters. These spicules generally have each end similar and may be smooth or spiky. In the inner choanosoma, within which are placed the feeding chambers of the sponge, elongate spicules are placed in a reticulate arrangement. These spicules generally have one end pointed and the other blunt.

Skeletal arrangements and individual spicules from various Myxillidae, from Hooper & Van Soest (2002).

Mixed in amongst these larger megasclere spicules are smaller microscleres that do not form part of the main structural skeleton, though presumably they do help hold the sponge body together. In myxillids, the microscleres generally take the form of anchorate chelae, small curved structures with incurved rounded prongs at each end. Members of the boreal genus Melonanchora have a mixture of chelae and a different type of microsclere shaped like a ribbed rugby ball (Santín et al. 2021). In the Indo-West Pacific genus Psammochela, growing sponges will also incorporate sand from the surrounding environment to supplement the microscleres (de Voogd 2012).

Growth habit of Myxillidae can vary from encrusting to massive to branching. The species Stelodoryx procera, found around the Azores, has a distinctive growth habit with a flattened main body at the end of an elongate stalk. On the whole, though individual species may be distinguished by growth habit, species within a single genus may differ greatly in form. For determining genera, examination of spicules is really the only way to go.

REFERENCES

Hooper, J. N. A., & R. W. M. Van Soest. 2002. Systema Porifera: A guide to the classification of sponges vol. 1. Kluwer Academic/Plenum Publishers.

Santín, A., M.-J. Uriz, J. Cristobo, J. R. Xavier & P. Ríos. 2021. Unique spicules may confound species differentiation: taxonomy and biogeography of Melonanchora Carter, 1874 and two new related genera (Myxillidae: Poecilosclerida) from the Okhotsk Sea. PeerJ 9: e12515.

Voogd, N. J. de. 2012. On sand-bearing myxillid sponges, with a description of Psammochela tutiae sp. nov. (Poecilosclerida, Myxillina) from the northern Moluccas, Indonesia. Zootaxa 3155: 21–28.

Gathering seeds and carrying tiny boulders in the desert: Harvester ants, Pogonomyrmex spp.

 

Harvester ants grapple with bird seed placed just outside their nest in the Mojave Desert.

 

With weather still a bit dreary in the DMV, let’s travel to the Mojave Desert in southern California to warm up and meet some really cool desert denizens, harvester ants. In previous episodes we visited home-invading odorous house ants as they raided pantries in search of sweets and herded honeydew-squirting aphids on peony blossoms outdoors. Unlike many ants that carbo-load on nectar and honeydew, harvester ants thrive on long chain and complex carbohydrates, lipids, and proteins found in the seeds of plants. These ambitious foragers get their name by harvesting seeds that serve as the major source of food for their colony. Red harvester ants greet the day by sending patrollers from the hidden depths of the colony to inspect the area immediately around the colony and beyond to distances up to a 20-minute ant-walk away. The return of patrollers signals the colony to muster forager ants to begin the busy task of collecting seeds from nearby plants. These dauntless workers may spend up to an hour on their journeys and venture 20 meters from the colony to collect seeds and bring them back to subterranean granaries in their colony.

On a sandy road in the Mojave Desert, a colony of harvester ants works at a fevered pitch. Watch as they collect seeds for their granary and excavate sand to enlarge their subterranean home. Harvester ants play a key role in dispersing seeds of many plants in the high desert.

Seed harvesting is not entirely bad for desert plants as some seeds are lost along the way home during peregrinations of foragers. Some accounts tell of seeds sprouting in over-filled harvester ant galleries, giving rise to new desert plants. Either way, harvester ants are important seed dispersal agents for propagules of many different species of plants. In fact, some plants have taken this relationship to a higher level and produce seeds with elaiosomes, structures packed with lipids, proteins, vitamins, and other nutrients that are highly attractive to ants. This form of ant-assisted seed-dispersal is known as myrmecochory. Why would plants make an evolutionary investment to manufacture energy-rich dispersal structures for their seeds? Scientists provide evidence that seed-dispersal by ants may reduce competition between parental plants and their offspring or competition between their offspring and other species of plants. Dispersing seeds may also derail gluttonous seed-eaters like small mammals that might devour an entire crop of seeds concentrated beneath a parental plant. Also, ant colonies often occupy nutrient rich pockets of soil where plants can thrive. Convincing ants to carry their seeds to these favorable microhabitats is a clever move on the part of a plant.

Red harvester ants are known by many as the entertaining occupants of “ant farms” sold to children and schools. Ant farms are engaging and educational but, as some have learned firsthand, harvester ants can pack a memorable sting. On the famous and amusing Schmidt sting pain index, pain associated with the sting of red harvester ants is described as “Like using a drill to excavate your ingrown toenail.” Yikes! Having said this, I will share that as I photographed and recorded harvester ants for this episode, dozens of ants explored my hands, arms, and body without delivering a bite or sting. Lucky me, I guess.

Acknowledgements

We thank our hosts Robin and Max at the High Desert Eden for sharing their harvester ants, stars of this episode. Two remarkable references, “The Regulation of Foraging Activity in Red Harvester Ant Colonies” by Deborah M. Gordon, and “The Ants” by Bert Hölldobler and E. O. Wilson, were used to prepare this episode.

Succulent Orchids | Catalogue of Organisms

With over 1200 known species found in Asia and Australasia, Dendrobium is one of the largest currently recognised genera of orchids. As with other examples of such 'super-genera', the question of how to best handle such a monster has been fiercely debated. In 2003, Australian botanist M. Clements proposed dividing Dendrobium between numerous segregate genera, noting (among other reasons) that the genus as previously recognised was not monophyletic. However, Clements' system does not seem to have garnered widespread usage with other orchid systematists preferring to retain a broad concept of Dendrobium (excluding some of the more egregious outliers) that largely corresponds with its established usage (e.g. Schuiteman 2011). Nevertheless, many of the subdivisions promoted by Clements remain recognised as well delimited groups. One such cluster is the assemblage of species recognised as Dendrobium section Aporum.

Growth habit of Dendrobium sect. Aporum, copyright Tony Rodd.

Species of section Aporum are epiphytes found in lowland forests of south-east Asia, extending eastwards to New Guinea and the Solomon Islands. Members of this section have thin stems that are erect at first but tend to become pendulous as they lengthen. Leaves are fleshy and equitant: that is, they are folded longitudinally with what would otherwise be the two sides of the dorsal surface fused, except at the base where they overlap with opposing leaves. The stem may be more or less completely concealed by the leaf bases. Tips of the leaves end in a point. Flowers are borne singly or in clusters, arising laterally on the stem between leaf nodes or at the tip of the stem alongside a terminal scale. The flowers may be subtended by persistent chaffy bracts. They are generally small and fleshy and tend to be short-lived, wilting after just a few days.

Flowers of Dendrobium anceps, copyright Aqiao HQ.

The functional significance of the Aporum section's distinctive leaves remains uncertain. As noted by Carlsward et al. (1997), the fleshy leaves might be taken as an adaptation to water retention. However, though access to water is a consistent concern for epiphytes, the humid rainforests in which Aporum species are found hardly seem the driest of places. Conversely, the effective even distribution of stomata on both sides of leaf resulting from their equitant condition may make it easier for excess water to be released from the plant.

Dendrobium distichum, photographed by Ronny Boos.

Orchids in general are, of course, most often considered by people as ornamental plants. My impression is that the various Aporum species tend not to be among the most widely grown of species though their unusual growth habit might attract interest. This may be due to them not being the easiest of orchids to maintain; they appear to require high humidity and warm temperatures to thrive with a cooler, drier period in the non-growing season. Among the more popular species are Dendrobium anceps and D. keithii, both of which produce small greenish flowers. Those of D. anceps have been described as having a distinct "apple pie" fragrance. Of course, if you happen to be wandering through the jungles of south-east Asia, you might well discover these plants growing of their own accord.

REFERENCES

Carlsward, B. S., W. L. Stern, W. S. Judd & T. W. Lucansky. 1997. Comparative leaf anatomy and systematics in Dendrobium, sections Aporum and Rhizobium (Orchidaceae). International Journal of Plant Sciences 158 (3): 332–342.

Clements, M. A. 2003. Molecular phylogenetic systematics in the Dendrobiinae (Orchidaceae), with emphasis on Dendrobium section Pedilonum. Telopea 10 (1): 247–298.

Schuiteman, A. 2011. Dendrobium (Orchidaceae): to split or not to split? Gardens' Bulletin Singapore 63 (1–2): 245–257.

The Huenellidae | Catalogue of Organisms

Researchers who deal with the modern marine fauna are used to thinking of brachiopods as a marginal group, their diversity greatly overshadowed on a global scale by the superficially similar bivalves. However, modern brachiopods are but a shadow of their former selves; for much of the Palaeozoic era, their relationship with the bivalves was the inverse of today. Many are the brachiopod lineages that came and went over this time.

External views of ventral (left) and dorsal valves of Huenella triplicata, from Walcott (1924).

The Huenellidae were an assemblage of brachiopods that lived during the late Cambrian and early Ordovician (Amsden & Biernat 1965). They represent early representatives of the Pentamerida, a Palaeozoic order of fairly generalised-looking brachiopods. Within the Pentamerida, they fall within the suborder Syntrophiidina. Syntrophiidinans as a whole are rarely found in the fossil record and as a result remain poorly known. Members of the suborder share a distinctive shape with biconvex valves marked by a dorsal fold and ventral sulcus. That is, the midline of the shell is raised above either side with the ventral valve forming a 'valley' to match the raised 'hill' of the dorsal valve. What, if anything, was the purpose of this arrangement I wouldn't know but modern brachiopods often inhabit locations with a lot of organic silt and/or fine sediment. Perhaps the uneven level of the syntrophiidinan shell helped protect it from burial by a shifting substrate.

Interior view of ventral valve of Radkeina taylori, from Laurie (1997), with scoop-shaped spondylium at upper midline.

Families of Syntrophiidina may be distinguished based on the development of the spondylium, an internal projection at the base of the ventral valve that provided an attachment site for the shell muscles. Members of the Huenellidae possessed either a sessile spondylium or a pseudospondylium, a spondylium-type structure rising from the internal surface of the valve itself rather than from the hinge. Amsden & Biernat (1965) recognised a division of the huenellids between two subfamilies based on the development of the brachiophore plates, projections on the inside of the dorsal valve that would have supported the lophophore. Members of the Huenellinae possessed more developed brachiophores than members of the Mesonomiinae. Outer ornament of the huenellid shell varied from more or less smooth with weak concentric ridges to costate with distinct radiating ridges.

Phylogenetic relationships within the Syntrophiidina do not seem to have been established in detail but the early appearance in the fossil record of huenellids at least raises the question of whether they included the ancestors of later families. As well as other families of the Syntrophiidina, candidates for descent would include members of the suborder Pentameridina as well as of the related order Rhynchonellida. This latter order includes species which survive to the present day so the possibility exists that while the huenellids themselves may be long gone, their legacy may yet live on.

REFERENCE

Amsden, T. W., & G. Biernat. 1965. Pentamerida. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt H. Brachiopoda vol. 2 pp. H523–H552. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas Press: Lawrence (Kansas).

From the Bug of the Week Mailbag: Who’s that big spider hanging out on my bedroom drape? Fishing spiders, Pisauridae

 

Sometimes found in homes, fishing spiders are among the largest of hunting spiders found in the DMV.

 

Discovering a large fishing spider hanging out on a bedroom drape can give one a bit of start. Image credit: Diane Pedicini

Recently we met two very large orb-weaving spiders, the golden silk spider and the Jorō spider, one of which, the Jorō, seems poised to expand its range northward along the eastern seaboard. But guess what? We already have several other impressively large spiders that are native residents in the DMV. Recently I received a text message from a friend with an image of a beautiful large fishing spider snuggled in the folds of a bedroom drape. Whether the spider had been loafing indoors all winter or simply moved in during a brief warm spell remains a mystery. Nonetheless, this oversized arachnid certainly left a memorable impression on my friend.  

Fishing spiders, in the genus Dolomedes, are often found near or on water, but they also wander forests and suburban landscapes and make startling appearances in homes and outbuildings. On more than one occasion, fishing spiders have greeted me in the basement or when I opened the door of my tool shed. Fishing spiders do not build webs to capture prey. They actively hunt and consume a smorgasbord of aquatic and semiaquatic animals; vertebrates such as fish, tadpoles, and toads, and a wide variety of invertebrates, with damselflies, water striders, aquatic beetles, and midges commonly on the menu. As with many other species of spiders, they have the somewhat disturbing propensity to eat other members of their species including youngsters and, for the females, their suitors. Fishing spiders are patient, clever hunters. With hind legs anchored on shore and forelegs outstretched on the water, they capture prey on and just below the surface when hapless victims venture too near. Special non-wettable hairs on their legs allow fishing spiders to ride the surface tension of water, enabling them to run or sail across the surface of a pool or stream.  

High on the Massanutten Mountain of Virginia a bench sits near a gentle stream, home to remarkable numbers of large fishing spiders. While the Zen-like tranquility of this spidery sanctuary may appeal to arachnophiles, arachnophobes may choose to relax elsewhere.

Members of the pisaurid clan also go by the name of nursery web spiders, so called for their habit of building a small web to serve as a refuge for tiny spiderlings emerging from an egg sac. Accounts suggest that fishing spiders can deliver a bite of similar severity to the sting of a bee or wasp. My experience with fishing spiders is that they are quite docile and willing to pose politely for photographs. However, I am not recommending that you try handling one. What of my friend and her fishing spider? She grabbed her handy spider-catching-cup, scooped up the spider, and released it back to the wild, a happy ending for human and spider.     

Acknowledgements 

Bug of the Week thanks Diane for sharing her image of a home invading fishing spider and providing inspiration for this episode. The excellent article “Prey use of the fishing spider Dolomedes triton (Pisauridae, Araneae): an important predator of the neuston community” by Manfred Zimmermann and John R. Spence provided a detailed dietary account of a common, widely distributed fishing spider.  

To see a fishing spider capture a minnow, please click on the following link: https://www.youtube.com/watch?v=nEKRWEo1PSI