Bug o’the Week – Two Odd Little Flies

Bug o’the Week
by Kate Redmond

Bug o’the Week Two Odd Little Flies

Greetings, BugFans,

The BugLady loves finding species she’s never spotted before – there are many thousands of insects she has yet to photograph, but that’s a matter of “right time; wrong habitat; more road trips.”  This year’s new bugs were mostly wasps, flies, and katydids – stay tuned.  And, as vintage BugFans know, the combination of the BugLady’s hyperopia (farsightedness) and her camera lenses (first a 50mm macro lens, then a 70, and now a 100mm) lure her into the world of little stuff.

They are in different families, but (besides size), what today’s two flies have in common is a very limited on-line presence.

FLY #1 – Heteromyia prattii

People frequently ask the BugLady about the clouds of midges they see dancing in the air, especially at the start and end of the bug season.  Those are mostly cold-tolerant species of non-biting midges in the family Chironomidae – fragile, mosquito-y-looking flies with long front legs https://bugguide.net/node/view/2260548/bgimage.  When she found this little fly in the brush near a wetland in June – a fly with a husky-looking thorax, bulging front legs, patterned wings, and extraordinary back legs – she was clueless (thanks, as always, PJ). 

It’s in the family Ceratopogonidae, the Biting midges (aka Punkies and No-see-ums).  Googling No-see-ums results in a flood of Extension and Exterminators sites.  Why?  Many female Biting midges sip the blood of reptiles, of humans and other mammals, and even of other insects in order to fuel their egg-laying.  To this end, their mouthparts are adapted for slicing through skin.  Among their targets are humans who are enjoying the outdoors – their bite is painful; the aftermath is irritating; and the lesions may last for weeks if the victim is allergic.  To top it off, some Biting midges can be vectors of disease in humans and livestock, here and abroad (none affect humans in North America).  Males don’t bite, and both males and females are fond of nectar.   

Biting midges are found across the continent and around the world.  Their larvae grow up in moist/wet, sheltered spots, and the adults are found in early summer in woodlands and around wetlands, both saltwater and fresh. 

Heteromyia prattii (no common name) is found in the eastern US and into southern Canada, but most of the dozen or so other genus members are tropical.  Its larvae live in shallow water and wet edges.  Like other Ceratopogonids, the adults are small – about 4mm (¼”-ish).  Here are some better pictures than the BugLady managed https://bugguide.net/node/view/2265258/bgimagehttps://bugguide.net/node/view/1020149/bgimage

About this species, little has been written, but more is known about its tribe, Heteromyiini.  In a paper published in 1978, Wirth and Grogan summarized the natural history of the tribe, going back to early observations of the fly.  They wrote So far as known, the adult females are predaceous on chironomid midges and other smaller, soft-bodied insects,” and they quoted from an 1856 paper “The species whose femora are armed with spines make a prey of other small insects, which they pierce with their sharp proboscis.”  A century later, Downes wrote that “The females of insectivorous Ceratopogoninae (typical genera: Ceratopogon, Stilobezzia, Clinohelea, Palpomyia) feed on small insects that are captured in flight. The prey is almost always the male of species of Nematocera and Ephemeroptera, and it is frequently, and probably typically, captured in the male swarms (mating swarms) that are so often produced in these groups. They thus reach, perhaps almost indifferently, the male swarm of their own or another species and proceed to capture prey.”  His account included a picture of a female Biting midge eating the male she was copulating with.  The larvae feed on invertebrates that are even smaller than they are, newly-hatched midges, and egg masses. 

FLY #2 – Dilophus stigmaterus (no common name)

The BugLady noticed Fly #2 when she was hauling her gear up the stairs of the hawk tower in September.  A few of the goldenrods at the base of the tower were covered with these speedy little flies, but plants not too far away had none. 

They’re in the March fly family Bibionidae, called March flies because many of the species emerge in spring.  If you’ve been to Gulf Coast, you’ve probably encountered swarms of March flies called Love bugs, in flagrante delicto (second meaning) (about Love bugs, bugguide.net says that because they became very numerous very abruptly, “There are a number of popular myths about this species, including that it was a lab creation designed to control mosquitoes.”).   

It’s not surprising that the BugLady saw a bunch of these flies.  March fly larvae live gregariously on/in the ground and under leaf litter (some are found in compost heaps), eating rotting plants and live plant roots and contributing to soil building.  They often emerge as adults synchronously, forming large mating swarms.  Females lay their eggs in small holes that they dig in moist soil.  The adults’ brief lives are focused on romance.  Those species that feed (not all do) eat nectar, pollen, and honeydew, and some March flies are important pollinators, especially of irises and orchids.

Dilophus stigmaterus is sexually dimorphic – males are all black https://bugguide.net/node/view/538047/bgimage, and females have a reddish thorax https://bugguide.net/node/view/1158066/bgimage, and both have a ring of tiny spines on their front tibias.  A long “nose” (rostrum) that is about as long as the antennae, and extended mouthparts that are about three times as long are key characteristics for the species.  Curious about how Dilophus stigmaterus lives its life?  The BugLady is, too, but other than a very detailed anatomical description of the species written by WL McAtee in 1922, and the fact that they’ve been recorded nectaring on Boneset, she couldn’t find anything else about them.  Remember – according to the Smithsonian, there are around 91,000 described species of insects in the US and probably another 73,000 waiting to be discovered/described.  While they all do their bit to make the world go ‘round, many do so very unobtrusively. 

Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’the Week – And Now for Something a Little Different XV – Royal Catchfly

Bug o’the Week
by Kate Redmond

Bug o’the Week And Now for Something a Little Different XV Royal Catchfly

Greetings, BugFans,

The BugLady had a long overdue “Oh Duh!!!”moment recently when BugFan Freda asked her if she realized why Royal Catchfly flowers were named Catchfly. Nope – hadn’t thought about it (insufficient scholarship).

Freda had just discovered, to her horror, that she might be aiding and abetting pollinator murder. Did the BugLady know that the Royal Catchfly was, in fact, a pollinator deathtrap? She had planted a small patch of native wildflowers in order to attract pollinators, and while she was admiring the Catchfly’s beautiful red flowers, she noticed a dead bumblebee. She took a closer look and saw a dead honeybee, one very much alive honeybee that was completely stuck and was trying to pull free from the sticky plant, and a small leafcutter bee that was in the same predicament (and when she gently pried a bee out of the glue, it remained so sticky that it couldn’t fly). There were at least two dead, and two dying bees in her pollinator patch.

Thanks, Freda, for the question (and for most of the pictures).

First off, what’s a Royal Catchfly?  It’s a brilliantly red, native wildflower in the Pink/Carnation family Caryophyllaceae and in the large genus Silene.  Silene is a complicated genus, and various aspects including its genetics, speciation, and the complicated reproductive strategies of some species have been studied for a long time.  Varieties of Silene are planted in perennial gardens and sold by florists, and some, like the non-native Bladder campion (Silene vulgaris) are eaten https://www.minnesotawildflowers.info/flower/bladder-campion.   

Royal catchfly is historically a plant of prairies, savannahs, woodland openings, roadside edges, and railroad rights-of-way, and today it’s considered widespread, but patchily distributed.  Over much of its range, which lies from Kansas and Oklahoma to Ohio, down to northern Florida, it’s considered to be Rare, Endangered or Threatened, and it’s been extirpated (driven locally extinct) from a few states due to habitat loss, invasive plant thuggery, shade, lack of fires, and humans with shovels.

Royal catchfly (Silene regia), and a number of other Silene species, are called “catchfly” because they catch flies.  They are adorned with sticky, gluey hairs (glandular trichomes) on the calyx (the green “vase” that’s formed by the sepals at the base of the flower) and on the upper stems.  The calyxes of older flowers that have shed their petals are a bit tacky, but not actively gluey like the younger flowers, and the leaves are fuzzy but not sticky.    

The sticky hairs (and some stiff, downward-pointing hairs toward the bottom of the plant) are very effective in stopping insects that might try to climb up the stem toward the flower (though one author had seen some aphids and their guardian ants navigating the stems).  They’re equally effective in deterring “nectar robbers” – insects like bumble bees whose tongues aren’t long enough to reach the nectar prize from the top of the flower, so they chew their way through the calyx from the side, sip the nectar, and don’t do any pollinating at all.  One author says that the plant is “selecting for” airborne pollinators,” the chief of which is the Ruby-throated hummingbird, though moths with long proboscises that hover in front of the tubular flower could get away with it, as can swallowtail butterflies.  Insects can’t see the color red (hummingbirds can), and apparently, although many insects can see ultra-violet light, a UV image of Royal catchfly doesn’t reveal any insect “come hither” signals.   

What happens after the bugs get caught? 

The logical leap is that having gone through the effort of catching them (producing the hairs requires an energy investment from the plant, after all) the catchfly uses them.  Some sources speculated that this kind of insect entrapment might be a step toward an eventual life of carnivory and wondered if the catchfly had any way to absorb the nutrients in its victims, like a sundew does.  In his Master’s Thesis in 2017, Garrett John Dienno held up two yardsticks to measure the Royal catchfly’s possible carnivory: “1) whether S. regia actively attracts, captures, and retains prey, and/or secretes digestive enzymes to facilitate nutrient absorption; and (2) whether it absorbs and translocates the resultant nutrients.”  Spoiler alert – No and No.  There is no insect-attracting nectar and no UV signal, and the glandular hairs do not secrete any digestive enzymes.  He concluded that “Instead, we propose the glandular trichomes on the S. regia calyx provide a passive defensive benefit to the flowers and seeds by protecting the very structures that are supporting their development.” 

The published word on the catchflies is a bit murky, though, and there’s some just plain bad information out there.  One otherwise respectable plant nursery noted that Royal catchfly comes from a carnivorous family (possibly the same nursery that once claimed that Cup Plant (https://www.illinoiswildflowers.info/prairie/plantx/cupplantx.htm) digests the insects that drown in the water pools formed by their perfoliate leaves).  The Pink family Caryophyllaceae is not known for carnivory, but the Order it’s in, Caryophyllales (a much bigger umbrella) does include some families with carnivorous plants (it also contains cacti and beets).  What a difference a few letters make!

A number of nursery catalogs and other publications state that because having small, rotting insects stuck to their stems would be unhealthy for Royal Catchflies, the plants get rid of the bodies by secreting enzymes that break them down before they “get putrid.”  Self-preservation rather than nutrition.  Way back in 1876, a Professor W. J. Beal wrote about a related plant that “We need not necessarily suppose that they are digested because they are captured by sticky plants.”  

A gardening site’s description of the related and equally sticky Night-flowering catchfly, which is pollinated by moths, said that “When the moth touches the plant it finds that it cannot get away easily and so is more likely to get covered in pollen, or release any pollen it is already carrying, as it tries to break free. This it will do, because the plant is not insectivorous and is only interested in temporary prisoners rather than permanent ones.”  So, happily, the plant’s intent is not to harm it.  

One nursery suggested that the stuck bugs might provide a feast for insectivorous birds.  The BugLady can picture the hummingbirds that come for nectar noticing the stuck insects and picking them off the plant (small insects are a regular part of their diets) but she can’t picture sparrows or chickadees doing that.  It’s possible that long-legged insects like wasps and yellowjackets, which forage for protein for their larvae, might check the catchfly’s offerings.

The British are not immune to this silliness.  Back in 2009, Scientists from the Royal Botanic Gardens, Kew and the Natural History Museum concluded that petunias, potatoes, and several other common plants were meat eaters – or at least on the way to being meat-eaters.  Why?  Because they have sticky hairs that trap bugs.  After making a big splash on both sides of the Pond, they walked it back a bit.  “However, some of the commonly accepted carnivores [like petunias] have not been demonstrated to have the ability to digest the insects they trap or to absorb the breakdown products.” 

They went on to say “Professor Mark Chase, Keeper of the Jodrell Laboratory at the Royal Botanic Gardens, Kew says, ‘…. many commonly grown plants may turn out to be cryptic carnivores, at least by absorbing through their roots the breakdown products of the animals that they ensnare. We may be surrounded by many more murderous plants than we think.’”  Nice save?

There’s a reason why scientists submit papers for peer review.

(The BugLady is reminded of Nathaniel Hawthorne’s short story “Rappaccini’s Daughter.”)

Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’the Week – Flies without Bios II
by Kate Redmond

Bug o’the Week by Kate Redmond

Flies without Bios II

Howdy, BugFans,

The BugLady is always ambivalent about photographing flies, even when they pose nicely.  There are a whole heck of a lot of species of Diptera (“two wings”) out there – 17,000 in North America and 150,000 worldwide (some estimates of the eventual total go as high as a million species) – so unless it’s a really dramatic fly, there’s a pretty good chance the picture will end up in the “X-Files.”  On the bright side, with that number of species, you can expect quite a bit of diversity – these are not all house fly-shaped-objects: https://bugguide.net/node/view/1126926, https://bugguide.net/node/view/2223038/bgimage, https://bugguide.net/node/view/1476962/bgimage, https://bugguide.net/node/view/2225982/bgimage, https://bugguide.net/node/view/2034795/bgimage, https://bugguide.net/node/view/35812.

Most insects have wings, and most insects that have wings have four of them.  The conspicuous, membranous flying wings on these “two-winged” flies are actually the front pair of wings – the hind pair has been modified into knob-shaped structures called halteres https://bugguide.net/node/view/130687, which provide sensory feedback that helps the fly maintain stability in flight.  Most flies feed on liquids that they sponge/suck up (in species like horse flies and mosquitoes, the sponging mouthparts are augmented by cutting blades that get the juices flowing).  As a group, flies spread both pollen and disease, though the former is more common than the latter.

The “Without Bios” series celebrates insects whose profile is low – insects that are neither big enough nor bad enough nor beautiful enough to have been studied much, if at all.

SNIPE FLIES (family Rhagionidae) are also known as “downlooker flies” because of their habit of perching head-downward.  They’re called Snipe flies because someone (in a fit of poetic license) thought that their protruding mouthparts looked like a snipe’s bill https://bugguide.net/node/view/1219348/bgimage.  They tend to have long legs, and while most are drab-looking, some are spectacular.  They like woods and wetland edges, and they prey on small insects.  Bugguide.net tells us that their taxonomy “has been unstable.” 

[Brief aside for non-birders.  Yes, snipe are a thing.  They are long-billed, medium-sized shorebirds https://www.allaboutbirds.org/guide/Wilsons_Snipe/overview that are often seen in the shallow water at the edges of wetlands.  The snipe hunt you went on at Camp didn’t have anything to do with actual Snipe.] 

SNIPE FLIES #1 – One of the more spectacular species.The BugLady has poked around at IDing this pair of flies off and on for years.  The heavy markings on their wing veins resemble those of the very spiffy Golden-backed Snipe Fly (Chrysopilus thoracicushttps://bugguide.net/node/view/1974388/bgimage, but – no Chrysopilus (“golden hair”).  Turns out that they are Chrosopilus foedus (no common name).  About them, the BugLady found that the adults perch on vegetation and on dirt roads, the larvae eat small worms, soft-bodied insect larvae, and grasshopper eggs, and like the Golden-backed snipe fly, they have a late spring flight period. 

The BugLady is interested in the etymology of entomology, and she discovered that the species name foedus has several unrelated meanings.  The first (a noun) is a “treaty, league, tie, bond, or pact;” second (an adjective) is “disgusting, foul, loathsome, ghastly, unclean, obscene, etc.

The BugLady encountered SNIPE FLY #2 (Rhagio hirtus) (maybe) along a woodsy edge, and she was fascinated by its behavior.  Every once in a while, as it ran around on the leaf, it would lower its head and push it around a bit on the leaf’s surface.  No idea.  (Well, two ideas – 1) some kind of myopic hunting behavior, or 2) it had been taken over by a brain-eating, zombie-making fungus.)

When she was prowling the dunes at Kohler-Andrae State Park last summer, the BugLady saw BEE FLIES, aka Humbleflies, (family Bombyliidae) of at least three species.  There are lots of Bee flies globally, but the lives of many of them are poorly known.  Adults are generally nectar feeders (they sip nectar through a non-retractable proboscis), and many are bee-mimics (and they make the requisite buzzing sound).  Larvae are parasitoids of ground-nesting insects like beetles, moths, and solitary bees and wasps. 

Mom locates a nest tunnel and lobs an egg into it while its creator is away looking for provisions for her eventual larvae (actually, Mom will throw an egg into any shadowy area that looks tunnel-ish, but she can afford to waste, because she can lay hundreds of eggs each day).  In order to add a little weight to the egg as she releases it, Mom picks up some sand, which she stores in a chamber (OK – a “psammophore“) at the tip of her abdomen.  Some sand adheres to the egg as it passes by, making it heavier and camouflaging it.  It’s theorized that since bee flies are soft-bodied, this method of laying eggs prevents them from close encounters with the owner of the tunnel, who may be upset by the intrusion and is packing a stinger.

The larvae are unusual in being very active in their first larval stage (hypermetamorphosis) – this lets them scurry down the tunnel and search for a host.  They let themselves into an egg chamber, and then settle down to normal larval speed, and eat the stored pollen and then the rightful owner of the cell.  The bee fly emerges the following spring in sync with the flight period of its target host. 

Bee Fly #1 – Exoprosopa fasciiata (probably), aka the Barred Bee fly, is pretty common east of the Great Plains.  “Fasci” means “band” and refers to the white band on the abdomen.

Bee Fly #2 – Exoprosopa fascipennis (no common name).  “Fasci” means “band,” and “pennis” means “wing.”  It’s found throughout the summer at beaches and sandy meadows over the eastern half of the continent.  It looks for the tunnels of Tiphiid wasps and sand wasps.  

Bee Fly #3 – Villa lateralis (probably) (bugguide says that because their markings are variable, “identification to species is tentative at best”).  Larvae of flies in the genus Villa feed on (in) the larvae of stag beetles, moths, horse flies, and ant lions that they find under the sand.

Available for all three bee fly species are extensive descriptions of every part of their anatomy, but not biographies.

The BugLady confesses (no surprise) that she’s always had a soft spot for predators, and ROBBER FLIES (family Asilidae) are amazing poster children for unapologetic meat-eaters.  There are lots of them – 7,500 robber fly species worldwide, 1,040 in North America, and about 100 in the Great Lakes area.  Robber flies have eyes worthy of a predator and long legs that the BugLady thinks look double-jointed somehow https://bugguide.net/node/view/1292828/bgimage).  They usually sport a beard (“mystax”- which is both Greek and Latin for “moustache”) https://bugguide.net/node/view/1692598/bgimage.  They like the sun, and they often perch on vegetation at woodland edges so they can scan for prey (the BugLady once saw one shoot straight up off a leaf in pursuit of a butterfly overhead).  They’ll go after bugs that are bigger than they are, including other robber flies, and one theory about the mystax is that it protects their faces from the stinging insects they catch.  Their larvae live in soil and rotting wood and eat small invertebrates that they find there.   

What happens when a robber fly’s hunt is successful?  Jeff Milton, in the Colorado Arts and Sciences Magazine, says it well: “Robber’s modified mouthparts form a stiff, hollow beak that serves first as a dagger, then as a hypodermic needle and finally as a straw. When robbers impale prey they inject both neurotoxins and digestive enzymes. The neurotoxins quickly subdue and soon kill the prey. The digestive enzymes turn the prey’s internal tissues to soup, but do not damage the tough chitinous exoskeleton, which now serves as a watertight container full of thick broth. Fluids are sucked through the beak until the carcass until is a dry husk.”

The STRIPE-LEGGED ROBBER FLY (Dioctria hyalipennis) (hyalipennis means “glassy wing”) is one of the more petite robber flies, and it’s easy to overlook.  It favors smaller prey like files, small wasps, sweat bees, and pygmy grasshoppers. 

According to Mike Reese in his awesome Wisconsin Butterflies website https://wisconsinbutterflies.org/ (which includes tiger beetles and robber flies), the SLRF is one of two non-native robber flies in North America.  It was first recorded in Boston in 1916 and was given a new name in its new country until scientists realized that it already had one in Europe.  It’s found across the northeastern quadrant of this continent and, inexplicably, in Oregon, and across Europe into North Africa.  The BugLady found articles about it in Finnish, Dutch, French, and Polish. 

Nota bene: when you’re writing the common name of a dipteran, the word “fly” is always separate – house fly, deer fly, etc.  When you write the name of a non-dipteran whose name includes “fly,” fly is incorporated – mayfly, dragonfly, firefly. 

Flies are some of the earliest insects to venture out onto the landscape in spring (especially the very cold-tolerant Chironomid midges).  Get ready!

Kate Redmond, The BugLady

Bug of the Week archives:

Become a Member

Take advantage of all the benefits of a Riveredge membership year round!

Learn More