Tag Archives: Fly

Identifying the Nicocles canadensis Robber Fly

Robber Fly (Asilidae), Nicocles sp.

It has taken a bit of time to finally sort out genus and species for this very cool Robber fly with beautiful caramel-brown mottled wings I spied the evening of June 6, 2025. It perched on a dried apple mint stem from last season, no doubt scouting the terrain to see what might be on the menu for dinner. Robber flies (Family Asilidae) are predatory. They catch other small invertebrates to eat, paralyzing them with special salivary digestive enzymes and then sucking up the liquified contents through the proboscis (Cannings, 2013).

Getting to an identification beyond Genus for this one has been incredibly frustrating, and complicating the process is the limitation of the key I was using (Wilcox, 1946), which primarily describes male specimens.

Robert Cannings has studied the Asilidae for many years in British Columbia and states this genus “sorely requires systematic attention.” I finally just gave up and reached out to Rob for help. He wrote me and said, “I’m pretty sure this is Nicocles canadensis. It’s a female, and some females are difficult, even when under a scope, because the Wilcox key, which is the best we have for now, deals with them poorly and concentrates on males. Nicocles canadensis is the species in the genus most often seen on BC’s south coast and, I assume, in your area.”

This is the only Nicocles fly I’ve ever found on our property on San Juan. According to Rob’s 2014 publication (linked in the references below) in Canada, ” Nicocles canadensis is restricted to Garry oak savanna and adjacent dry woodland on southern Vancouver Island (Saanich is the type locality),” so I anticipate this may be similar for our neighboring area.

Check out the attached references if you are interested in learning more about Robber Flies in our region.

Thanks for reading!

References

Cannings, R.A. 2014. The Robber Flies (Diptera: Asilidae) of Western Canadian Grasslands. 10.3752/9780968932179.ch7. https://www.researchgate.net/publication/268524943_The_Robber_Flies_Diptera_Asilidae_of_Western_Canadian_Grasslands

Cannings, R.A. 2013. Robber Flies (INSECTA: DIPTERA: ASILIDAE) Of The Montane Cordillera Ecozone.

Cannings, R.A. 1994. Robber Flies (Diptera: Asilidae) new to Canada, British Columbia, Yukon,
and the Northwest Territories with notes on distribution and habitat. J. Entomol. Soc.
British Columbia
: 91: 19-26. https://www.biodiversitylibrary.org/part/213777

Cole, F. R. 1969. The Flies of Western North America. University of California Press. Berkeley and Los Angeles.

Fisher, E.M., and Wilcox, J. 1997. Catalogue of the robber flies (Diptera: Asilidae) of the
Nearctic Region. Unpublished preliminary draft.https://staff.royalbcmuseum.bc.ca/wp-content/uploads/2013/08/Catalog-Nearctic-Fisher-Wilcox-1997-manuscript-copy.pdf

Geller-Grimm, F. 2008. Robber Flies (Asilidae). Internet site at http://www.geller-grimm.de/asilidae.htm

Melander, A.L. (1924) Studies in Asilidae (Diptera). Psyche [1923] 30: 207-19. https://onlinelibrary.wiley.com/doi/pdf/10.1155/1923/83461

Wilcox, J. 1946. New Nicocles with a key to the species (Diptera, Asilidae). Bulletin of the Brooklyn Entomological Society 40 (1945): 161-165; New York – Lancaster. https://www.biodiversitylibrary.org/page/50573094#page/180/mode/1up

Fantastic Fly Friday

I thought I’d write up a short post about all the wonderful flies (and a few others) pollinating our plum trees in this cool spring weather. Why feature the flies? Well, for starters, the plum tree blossoms are white and flies love the color white. Another reason to feature the flies is because they are under-recognized and under appreciated, but very important pollinators. Some fly larvae even serve as pest predators, eating aphids. Others, like the tachinid fly below, use caterpillars that defoliate trees as hosts for their larvae to develop. Flies are also awesome because they do not sting! Some even “dance!” My favorite fly hasn’t shown up yet. It’s a Conopid Fly. More about that one later though…

Tachinid Fly (Epalpus signifier)

This past week in the media, there have been so many posts about the decline in honey bees. While there are some (unwanted) honey bees showing up on days when the temperatures climb above 50 degrees, honey bees aren’t active if it is cooler. Flies, on the other hand, are quite busy at work pollinating and do just fine when it might only be 40 outside. Flies are awesome! They need our support and appreciation.

I’d like to add (and I do know something about this because of my entomology background), that honey bees are just not necessary on San Juan Island. In fact, they might even be a very bad thing. They showed up at our plum tree as the temperature warmed up the other day, and as they arrived in increasing numbers, they kicked off ALL of the native pollinators that I had been observing. 😦

For honey bees to fly out of the hive and forage, they need temperatures above 50 degrees. In my experience keeping bees (as part of my graduate school work), they typically do not survive well on the island unless they are fed supplemental sugar water. Think about the ecological footprint of growing sugar to feed the bees!

Feeding honey bees attracts (and supports) the buildup of yellow jacket populations which are attracted to honey bee hive resources (including eating the honey bee brood developing in the hive), and honey bees also bring pests and pathogens that impact native bees (especially bumble bees). One more thing! If you are growing tomatoes, bumble bees are your pollinators, not honey bees.

I hope you will read and consider this recent study published about how honey bees were negatively impacting native pollinators on Giannutri Island in Italy. They were causing a decline in the populations of wild bees. In fact, the study cited an “alarming 80% decline in wild bee abundance over 4 years” (Pasquali et al. 2025). You can access this study to read it yourself here: https://www.cell.com/current-biology/pdfExtended/S0960-9822(25)00262-3

Enjoy the gallery of the native pollinators that I was fortunate to photograph and be able to share. Be a fly fan! Be a native bee fan! Learn about our unseen, but important night time pollinators (moths), and PLEASE LEAVE THE HONEY PIGS for the mainland industrial farm operations.

Syrphid Fly (Tribe Syrphini )
Golden Dung Fly (Scathophaga stercoraria)
Cluster Fly (Genus Pollenia)

Musca autumnalis
Sericomyia chalcopyga Western Pond Fly
Sericomyia chalcopyga Western Pond Fly
Bibionid Fly (Bibio sp.) and Hybotidae Dance Fly (Bicellaria sp.)
(Melanostoma mellinum) Variable Duskyface Fly

References

Anderson, H. L. D. (2024). Nocturnal moth communities and potential pollinators of berry agroecosystems in British Columbia (T). University of British Columbia. Retrieved from https://open.library.ubc.ca/collections/ubctheses/24/items/1.0447737

KEARNS, C. A. 2001. North American dipteran pollinators: assessing their value and conservation status. Conservation Ecology 5(1): 5. [online] URL: http://www.consecol.org/vol5/iss1/art5/

Pasquali, Lorenzo & Bruschini, Claudia & Benetello, Fulvia & Bonifacino, Marco & Giannini, Francesca & Monterastelli, Elisa & Penco, Marco & Salvati, Vania & Simbula, Giulia & Skowron Volponi, Marta & Smargiassi, Stefania & van Tongeren, Elia & Vicari, Giorgio & Cini, Alessandro & Dapporto, Leonardo. (2025). Island-Wide Removal of Honey Bees Reveals Exploitative Trophic Competition with Strongly Declining Wild Bee Populations. 10.2139/ssrn.5081459. https://www.sciencedirect.com/science/article/pii/S0960982225002623#:~:text=Article-,Island%2Dwide%20removal%20of%20honeybees%20reveals%20exploitative%20trophic%20competition,strongly%20declining%20wild%20bee%20populations

Ssymank, A., Kearns, Bonn & Carol. Flies – Pollinators on two wings. The Diptera Site. https://diptera.myspecies.info/diptera/content/flies-–pollinators-two-wings

April 5, 2025 – Herman finds a fly

That’s right! Herman the Persian found something interesting in the yard when we were outside sunning ourselves a bit this afternoon. He found one of the Bibionid March flies (a female). If you read my post yesterday https://buggingyoufromsanjuanisland.com/2025/04/04/nuptial-gifts/, you might note that Bibionid flies were being hunted by Empis flies who rolled them into little balls as nuptial gifts used to woo the lady Empids to mate.

Female Bibionid fly digging chamber to lay her eggs.

Evidently, a few of these Bibionid flies escaped that destiny and actually mated with their own kind. THIS one, that Herman found, was hard at work digging her own death chamber where she would expire soon after laying her eggs. Incidentally, the adults are very short-lived, and in fact, live only about 5-7 days with the primary objective of mating, and for the adult female to lay her fertilized eggs. In spite of their brief existence, adults are also thought to be important early pollinators of orchard trees. Yes, you heard me right! Flies don’t get nearly as much credit for pollinating as they deserve to receive.


I watched her digging with her fossorial forelegs. It seemed to be an impossible task, but she made slow and steady progress. She was still hard at work before we went back into the house about half an hour later. I marked the spot with a rock so I could go back and check, but I suspect even with the rock nearby as a marker, it will be next to impossible to detect any disturbance in the soil tomorrow. We’re supposed to get rain this evening.


In approximately 30-35 days, the eggs she lays will hatch underground. The larvae will live in the top layer of soil and feed gregariously on leaf and needle litter, decaying organic matter, and sometimes on below-ground parts of plants.

If you’re curious, you can read more about Bibionid flies in the attached links. I did see some additional Empis fly males dancing about today with their Bibionid “balloons” or nuptial gift balls for prospective mates.

Thanks for reading. 🙂

References

Bugguide.net. 2025. Family Bibionidae – March flies. https://bugguide.net/node/view/3834

Morris, H. No date. The larval and pupal stages of the Bibionidae. Entomological Department, Institute of Plant Pathology, Rothamsted Experimental Station, Harpenden. https://core.ac.uk/download/pdf/212009582.pdf

A Sedgesitter

This was Wednesday’s bug of the day. I’m a day behind writing up my post. Although I have tried to get out for a quick bug search every day, it’s been overcast and/or drizzly here this past week. I was excited to see this little fly hunkered down on a twig of our fruitless cherry tree, the tree that I whacked off as an unwanted upstart for several years before I discovered how interesting it is.

Western Forest Sedgesitter, (Platycheirus trichopus), I believe

That tree is a mini ecosystem: floral nectaries that feed the aphids, aphids, slave making ants that have fights to the death (winning) with the carpenter ants that try to invade our home every spring, and the birds that rip the leaves apart trying to get the aphids. Now I can add Syrphid flies to the list!

That’s what this is. A syrphid fly. Syrphid flies eat aphids. It would make perfect sense for this adult to lay eggs on the tree, though I’m not sure what would happen because the ants that farm those aphids are certainly willing to die defending them. I could definitely see the ants overtaking the syrphid fly larvae. Nevertheless, the fly flew off. Somewhere.

I believe this particular fly is the Syrphid fly species Platycheirus trichopus, the Western Forest Sedgesitter. While difficult to ID to species, I did reference the helpful ID guide by fly expert, Even Dankowicz. https://docs.google.com/presentation/d/19F1qRGpmNDgaGE13M2SMUBlI846JicTOYjIescjVTHw/preview?slide=id.g8918834f0e_0_92

This species, as mentioned earlier is pretty small at only about 6.8-9.4 mm. Geographic distribution ranges from the Rocky Mountains west from Alaska to Mexico (bugguide.net). Adults of this genus are known to feed on the pollen of wind pollinated plants like Willow (Salix sp.) and various grasses (Poaceae), and sedges (Cyperaceae). It is believed they are better adapted to activity in cooler temperatures and that fits with yesterday’s rather gloomy spring day.

Thanks for reading!

References:

Dankowicz, Even (2023). “Common Pipizini, Paragini, and Bacchini Species of the Southwestern U.S. (CA NV AZ UT NM CO)”The Fly Guide: Field/Photo ID for Flies. pp. 9–10.

Bugguide.net. 2025. Syrphidae. https://bugguide.net/node/view/196

Bubbles

Well, this little fly got my attention yesterday. We had a contest. The fly bet it could outlast my grip on my phone as I took video of the bubble blowing. We called a tie somewhere around the 4 minute mark when my hand was shaking and I was about to drop my phone. The fly, quite satisfied with its performance, waltzed about on the mint leaf and posed for a few still photos, after I got the blood flowing into my hand again.

This is a Black Blow Fly (Phormia regina) in the family Calliphoridae. These flies are found ranging throughout North America, Eurasia, and Hawaii. They are a species of importance in the science of Forensics. Blow flies are attracted to dung and carrion, and when found on a corpse, they can be used to estimate time of death. The larvae or maggots of sterile blow flies are also used in the cleaning of wounds, removing decaying flesh and secreting antimicrobial peptides as they feed (Díaz-Roa et. al. 2018). Occasionally, they can contribute to secondary myiasis “fly-strike” of wounds in livestock, wildlife, and pets.

Phormia regina Fly – San Juan Island, WA 07.11.2024

Why is the fly blowing bubbles? It’s not black bubblegum. I’m not sure why the bubbles were black in color. Perhaps something to do with what the fly had been eating. The fly is blowing bubbles to cool down and it’s actually called BUBBLING. Take a look at Ray Cannon’s Nature Notes and you’ll learn it’s part of an evaporative process where the fly moves a droplet of fluid in and out and of their buccopharyngeal cavity over and again before eventually swallowing it (Gomes et al., 2018, Cannon, R. 2020).

Phormia regina Fly – San Juan Island, WA 07.11.2024

Flies aren’t the only group that practices bubbling. Various species of Hymenoptera also use this method to cool themselves and also to evaporate the excess water from the food (nectar) they’ve consumed (Portman et. al. 2021).

Thanks for stopping by!

References and Further Reading

Cannon, Ray. 2020. Flies Blowing Bubbles. Ray Cannon’s Nature Notes. https://rcannon992.com/2020/09/07/flies-blowing-bubbles/

Díaz-Roa A, Patarroyo MA, Bello FJ, Da Silva PI Jr. 2018. Sarconesin: Sarconesiopsis magellanica Blowfly Larval Excretions and Secretions With Antibacterial Properties. Front Microbiol. Sep 28;9:2249. doi: 10.3389/fmicb.2018.02249. PMID: 30323791; PMCID: PMC6172317. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6172317/

Gomes, G., Köberle, R., Von Zuben, C. J., & Andrade, D. V. 2018. Droplet bubbling evaporatively cools a blowfly. Scientific reports8 (1), 1-7.

Murray, T. 2023. Species Phormia regina – Black Blow Fly. Bugguide. https://bugguide.net/node/view/53678

Portman, Z., Ascher, J. & Cariveau, D. 2021. Nectar concentrating behavior by bees (Hymenoptera: Anthophila). Apidologie 52, 1169–1194. https://link.springer.com/article/10.1007/s13592-021-00895-1

Know Your Pest Predators – Make Friends with Eudioctria sackeni

Eudioctria sackeni Robber Fly

This is one of my favorite garden residents (Eudioctria sackeni), or the Sacken Longhorn Robber. I remember the first time I saw one of these, I thought, “Wow, it’s an Ombre Fly!” If you didn’t know, “ombre” means the blending of one particular color hue to another, often from light tints to dark. The coloration in this particular fly is distinctly “ombre,” though it varies in individuals within the species.

Eudioctria flies are in the family group, Asilidae or Robber flies. They are voracious predators of small insects that can be pests of gardens and orchards. Here, you see this one enjoying a small dipteran (fly) of some variety, perched on the leaf of one of my mint plants. The mint is a popular scouting platform. On any given day in the summer, I’ll see 4 or 5 of these flies in a six foot strip of mint which has become quite abundant in the yard over the past few years. The mint seems to be quite attractive to pollinators, and it also provides shelter for other bugs and critters. Our little tree frogs love to sit in the mint too.

Reference and further reading

Species Eudioctria sackeni – Sacken Longhorn Robber. BugGuide. https://bugguide.net/node/view/60617

What’s Biting Me? Episode ONE, San Juan Sniper

I’m going to start a new bug series called “What’s Biting Me?”  

I’m starting this series because I have such bad reactions to bug bites in general, and I’m exasperated when people blame mosquitoes and spiders for everything.  Also, if you’re one of those who is tired of it getting crowded here in the San Juans, feel free to share this with anyone who is thinking about moving here – or with anyone you WISH would move off the island.   Maybe they’ll decide to live somewhere else.   😉


Epidode ONE, the San Juan Sniper

This is one of the Rocky Mountain Bite Flies (Symphoromyia sp.).  It’s a Snipe fly in the family Family Rhagionidae, and it bit my husband today.   Those are NOT my hairy legs.  They’re my husband’s.  

Rocky Mountain Bite Flies (Symphoromyia sp)

After getting some pictures, I went inside to look up what information I could find about the Genus and narrow down what species are in WA state. In doing so, I came across this interesting, and disturbing medical case report of a woman who had a severe allergic reaction to the bites of these flies.  Now this was in the 70’s, in Forks, WA, but if this fly had bitten ME instead of my husband, it’s very likely I’d be the next case write up.  

Rocky Mountain Bite Flies (Symphoromyia sp)

Attaching the paper in the link here if you care to read it.  The woman could have D-I-E-D from anaphylactic shock.  

You’ve been warned.  

No worries, just stay indoors and you’ll avoid being bitten by the San Juan Sniper.  


Symphoromyia Genus

Size: 4.7-9mm

Food: Females of some species of this genus are blood feeders. Symphoromyia females are common biting pests in the west. Males do not take blood meals. Both adults and larvae will prey on small insects.  

Habitat: Adults are commonly found in woods near moist places, often found on foliage or grass, positioned with head resting head downward. Larvae occur in moist meadow soil, moss, decaying wood (incl. galleries of wood-boring insects), under bark, occasionally in water (bug guide.net).

References and Further Reading

Aldrich, J. M. 1905. A Catalogue of North American Diptera. Smithsonian Miscellaneous Collections 46:680.

Bowser, Matt. 2017. Refuge Notebook: The bad biter par excellence. Peninsula Clarion. https://www.peninsulaclarion.com/life/refuge-notebook-the-bad-biter-par-excellence/#:~:text=Very%20little%20research%20has%20been,not%20known%20to%20transmit%20disease.

Bugguide.net. Family Rhagionidae (Snipe Flies). https://bugguide.net/node/view/116

Kerr, Peter H. 2004. REVISION OF THE GENERA OF THE RHAGIONIDAE OF THE WORLD (DIPTERA: BRACHYCERA). Doctor of Philosophy Dissertation. University of Maryland, College Park. https://drum.lib.umd.edu/items/7f964daf-76bd-467e-ac36-18a523ac5e5a

Turner WJ. A case of severe human allergic reaction to bites of Symphoromyia (Diptera: Rhagionidae). J Med Entomol. 1979 Feb 8;15(2):138-9. doi: 10.1093/jmedent/15.2.138. PMID: 448692 https://www.tesble.com/10.1093/jmedent/15.2.138

Mitten feet

This is one of my “Know your pest predators” posts, featuring one of our PNW flies. Flies are all too often maligned and under-appreciated. We think of flies as spreading disease and being a nuisance, yet many of them perform incredibly important jobs as pollinators and pest predators. Yesterday I was sleuthing flies in the yard and found these metallic green beauties. Here is a Dolichopus (“doe-LICK-uh-pus”) male and female. The “dolicho-“ part means “long”, and the “-pus/-pod” part means “leg” or “foot.”

Some species of Dolichopus males (like this one) have little “flags ” or “mitten” front feet they wave or flap around to woo the ladies. Reading about this very large group of flies has been interesting and you can learn more about their courtship behaviors in Van DuZee et al. (1921).

Dolichopus sp. male fly

These flies are predators of small, soft-bodied invertebrates as adults and during their larval stage. You can thank them for helping keep populations of aphids under control in your garden.

Dolichopus sp. fly (male)

You’ll find these flies in northern latitudes in North America. “Dolichopus species are among the largest and most common members of the family Dolichopodidae in North America. The majority of Dolichopus species prefer humid habitats and some are restricted to saltmarshes,” (Pollet et al. 2004).



References:

MARC A.A. POLLET, SCOTT E. BROOKS, JEFFREY M. CUMMING. 2004. “CATALOG OF THE DOLICHOPODIDAE (DIPTERA) OF AMERICA NORTH OF MEXICO,” Bulletin of the American Museum of Natural History, 283, 1-114,

Van Duzee, M. C., Cole, Fr R., and Aldrich, John Merton. 1921. “The dipterous genus Dolichopus Latreille in North America.” Bulletin of the United States National Museum. i–vi, 1-304, 16 pls. https://doi.org/10.5479/si.03629236.116.i

Key to male nearctic Dolichopus species here – https://digitallibrary.amnh.org/items/5c3c75c8-27ae-47e6-acac-59ec0c30d1cb/full

Hidden Daggers

Spring has arrived and with it comes beautiful daffodils popping up across the landscape, but also pollen, windy days, and those dreaded allergies many of us suffer from. I’ll bet as you’re reading, you’re might visualize little pollen grains as daggers that blow up our noses and make us sneeze! Personally, when I visualize pollen grains, I picture them as the equivalent of microscopic land mines. Even though pollen grains can be quite unique when viewed under a microscope and cause quite SHARP “achoo’s” into that handkerchief, there’s another DAGGER you’ll have to go search for in those daffodils.


Rhamphomyia fly - Dagger Fly on Daffodil
Rhamphomyia fly – Dagger Fly on Daffodil

When I first saw this bug and took some photos with my phone, I didn’t realize that EXTRA leg was not a leg at all, but a beak of sorts. More close up photos yielded some images of this particular specimen that reminded me of the sinister hood worn by doctors during the Plague that looks like a giant bird beak.

This BUG I found in the daffodils with the strange “beak” or proboscis, a scientific term for an appendage-like mouthpart of an organism, is a type a fly. The common or vernacular moniker being Dagger Fly.

Rhamphomyia fly - Dagger Fly on Daffodil
Rhamphomyia fly – Dagger Fly on Daffodil

From here, I’ll take you through my process of determining the fly’s classification. First off, to understand it is a FLY, you must look at the number of wings. Flies are taxonomically categorized into the insect order Diptera. Di=two and ptera = wings. Two wings or one pair of wings = FLY. Now the Flies or Diptera are an enormously diverse and large group of organisms. Fly classification or taxonomy is one of the hardest groups I’ve ever worked through and in my rudimentary assessment, I managed to identify my specimen as far as the Family Empididae or the Dance flies. This fly wasn’t exactly “dancing” though. It was poking its beak around in the daffodil, and there were several of them in one flower – all doing exactly the same thing.

Rhamphomyia flies – https://bugguide.net/node/view/8957

At this point, I turned to the fly group I belong to on a popular social media site. I posted my photos with date/location/and my suggested family (Empidiae), then asked if someone could help me with further classification. About two days later, I checked back. The suggestion in the comments was for Genus Rhamphomyia. It would be particularly challenging to identify this particular fly to species. Bugguide.net cites Arnett’s American Insects: A Handbook of the Insects of America North of Mexico, stating there are over 400 undescribed species in our area with 450 undescribed worldwide.


While Genus Rhamphomyia falls under the Empididae or dance flies, Rhamphomyia translates from Greek rampho ‘beak’ + plus myia ‘fly.’ Beak flies they are indeed!

Dagger Fly (Rhamphomyia sp.)

Delving past the taxonomical classification of the genus I discovered some interesting bits of information involving mating behaviors. Like other groups of flying insects, males and females will often form swarms of groups, sometimes referred to as leks. In the Rhamphomyia, these groups can be either all male or all female (a reversed-role lek) or mixed.

If the group is single sexed, it may be the opposite sex does not form a group, but rather enters the single sex group to select a mate. There may also be a group of females and a nearby group of males and individuals from each group will leave and mix with the opposite sex group to choose a mate. Different species of this genus may swarm at different times of the day. Some species may spend the entire day swarming, while others only a select time such as right before dusk or early morning. Swarm locations are selected around some sort of visual marker or landmark which may range from very specific ( a particular branch or limb overhanging a pond) or quite general (the southern slope of a hillside adjacent to a stream or a farm field).

The most intriguing behavior is the habit of male flies to collect and bring nuptial gifts to a female. Alcock (2016), describes this fascinating ritual where female flies gather in swarms low over open woodlands, high in treetops, or over grassy hayfields in early morning or late evening. The swarms lasted 1-2 hours each with female Rhamphomyia flies holding their highly ornamented legs wrapped around their abdomens. In these swarming female groups, males enter and gift their selected female a small insect for her to consume. Examples of tiny insects selected for nuptial gifts include drosophila flies, small syrphid flies, or tiny caddisflies (Alcock 2016). Kuiter, Findlater-Smith, and Lindhe (2017) recorded nuptial gifts to include “fungus-gnats (Myctophylidae), crane flies (Tipulidae), other Empididae flies, and occasionally small moths (Lepidoptera). ”


Reading a bit more led me to Funk and Tallamy (2000) who describe the plight of the female Dagger fly. She is unable to hunt for prey and wholly dependent on these nuptial gifts of protein necessary for development of her offspring. In the swarming leks, she seeks these nuptial gifts from male suitors in exchange for copulation.

While I didn’t witness the formation of swarming leks of these flies, I did find some handsome daggers hanging out in the daffodils. I kept reading and found they can use their beaks not only to pierce small insects, but also to pierce and extract nectar from flowers. As they feed, pollen collected on their bodies may be distributed to other flowers (Sezen 2015).

Rhamphomyia Dagger Fly on Daffodil

Probably the grand finale in my literature search yielded the paper written by Kuiter, Findlater-Smith, and Lindhe (2017) titled Pollination of the Bearded Greenhoods (Orchidaceae) by Dagger Flies (Diptera: Empididae). They describe a unique relationship between the orchid and another species of Dagger Fly. Located in Victoria,Australia, the authors document the case of mistaken identity – the male dagger fly is lured to the orchid by both chemical and physical attributes mimicking the female fly’s sex pheromones and her morphology.

While daffodils aren’t the orchid described by Kuiter et al, (2017), I considered their observations to offer one possible reason the flies I found could become so awkwardly stuck. Kuiter et al. (2017) suggest the flies observed bringing nuptial gifts to the Bearded Greenhood orchid (Pterostylis plumosa) are attracted by the orchids’ kairomones which mimic the Empididae female flies’ sex pheromones. In the case of this particular orchid, the hairy labellum inside the flower head acts as a visual cue, arousing the male who mistakes it for the hairy legs of a female Empididae fly (Kuiter et al, 2017). They believe the bearded orchids may have evolved the hairy labellum for holding the nuptial gift of the male fly just as females of the fly species have hairy legs for receiving the nuptial gift – a very species-specific relationship ensuring the orchid is pollinated.

I believe this relationship provides a possible explanation (at least for me) as to why I found deceased flies stuck within the filaments and stamen inside several daffodil flowers. I actually found four flowers with stuck flies, so it seemed more than merely coincidence. Is it remotely possible the species of male Dagger fly I found mistakes parts inside the daffodil flower for a female fly and cannot extricate himself from the situation? Mistaken identity? Or, did he merely shelter there in the cool of the night and expire in slumber? https://nossaorg.files.wordpress.com/2017/05/finalbeardedgreenhoodpollinatorlrs.pdf

Rhamphomyia Dagger Fly in Daffodil
Rhamphomyia Dagger Fly in Daffodil

I’ll end with a note of my own. Many of these relationships between plants and pollinators are highly complex, understudied, and/or, as in this group of flies, un-described. Many species of plants and animals, including and especially pollinators, are under immediate threat due to climate change, habitat loss, and land use changes. You can help by minimizing your impact and changing long-held habits. Avoid clearing around your property, try the “no-mow” approach. We mow only trails and leave the rest. Plant native plants, leave brush piles instead of making burn piles, build a smaller home, be a smart consumer. We are altering systems that enable our own survival. Get outdoors and learn about the diverse life that shares your space. Check out the iNaturalist app and see what you can record in your own backyard. These unseen living critters around us are unique, intriguing, and worth saving!

Thanks for reading!


View more photos in my Dagger fly gallery here:


Vocabulary

Leks – aggregation of (male) animals gathered to engage in competitive displays and courtship rituals, known as lekking.

Kairomone – allelochemicals where the chemical signals are favorable to the organism that receives the signal. A familiar example is the lactic acid component of human sweat that attracts the mosquito Aedes aegypti (Augustin, 2016).

Morphology -the study of the form and structure of organisms and their specific structural features.

Pheromone – semiochemicals that influence the physiology or behavior of members of the same species. They include sex attractants, alarm substances, aggregation pheromones and trail markings (Augustine, 2016).

Proboscis– tubular feeding and sucking organ of certain invertebrates such as insects.


References and Further Reading

Alcock, J. The Mating Behavior of an Undescribed Species of Rhamphomyia (Diptera: Empididae). J Insect Behav 29, 153–161 (2016). https://doi.org/10.1007/s10905-016-9545-5

Augustine, T.J. 2016. Kairomones. Organic Materials Review Institute (OMRI) https://www.omri.org/kairomones

Bugguide.net. 2003-2023. Genus Ramphomyia. https://bugguide.net/node/view/8957

Kuiter, R., Findlater-Smith, M.J., and Lindhe,R.E. 2017. Pollination of the Bearded Greenhoods (Orchidaceae) by Dagger Flies (Diptera: Empididae). Aquatic Photographics. Short Paper 1. https://nossaorg.files.wordpress.com/2017/05/finalbeardedgreenhoodpollinatorlrs.pdf

Funk, D. H., & Tallamy, D. W. (2000). Courtship role reversal and deceptive signals in the long-tailed dance fly, Rhamphomyia longicauda. Animal Behaviour, 59(2), 411–421. doi:10.1006/anbe.1999.1310
10.1006/anbe.1999.1310

Mischenko, M. and Frostic,M. 2009. Scanning Electron Microscope Still Image of Pollen Particles. Scientific Visualization Studio. NASA/Goddard Space Flight Center. https://svs.gsfc.nasa.gov/10394

Sezen, U. 2015. Common Mallow Pollinated By Dagger Fly. Nature Documentaries. http://naturedocumentaries.org/10098/common-mallow-pollinated-dagger-fly/

Western Calligrapher (Toxomerus occidentalis)

I sat outside today in the sunshine, forced convalescence if you will, exhausted and achey after getting my Covid Omicron Variant booster vaccine yesterday at the San Juan County Fairgrounds. My outdoor time was unfortunately cut short because we have been inundated with construction development noise. I’m fairly certain I will be forever challenged to have an amiable relationship with our newest neighbors. In part, because they sited their VACATION home, right in front of our view. Mind you, they could have moved over 100 feet and we would not have to look across the top of our driveway at their newly constructed 2nd home. It has definitely impacted us. We’ve lost a lot of our privacy out here in the woods. It was never my desire to have close neighbors. I am a bit of a recluse….which is what the new neighbor said about his wife, yet, it begs me to ask again, WHY DID YOU BUILD YOUR HOUSE RIGHT ON TOP OF US?

Oh, and the jackhammering! That noise is enough to make a person homicidal. We had an entire summer of jackhammering from the former owners of that property. Really, truly, that property should never have been zoned for development. Not any development. It’s partly (half) wetland, and the other half is bedrock. Imagine the task of trying to excavate enough to bury your septic lines down the hill when you have solid bedrock! Also, our house is on that same shelf of bedrock, so the hammering shakes the walls and vibrates the floors of our home in the process of all this construction. The development on this lot has gone on for multiple years. I’m really tired of the disruption.

I digress. Sorry, I just had to vent. San Juan Island would be a much friendlier place for wildlife and bugs and such if we didn’t allow anyone to build a 2nd, or 3rd home here. We are outgrowing our space and it isn’t pretty.

Here’s my bug of the day. This beauty is a Western Calligrapher Fly (Toxomerus occidentalis). I was mesmerized watching it rest on the mint leaf. The patterning on the dorsal side of the abdomen reminds me of some sort of totem design.

The adults of this fly species are pollinators. They lay eggs on plants near aphids and when larvae emerge they are predatory on the aphids. It is believed that late instar larvae overwinter, pupation takes place in the soil cavities in the spring and adults emerge later in summer. The name for this group of flies comes from Greek toxon ‘bow’ + meron ‘thigh’ (refers to the bow-shaped hind femur). You can see the curve in the first photo below, circled in red. Something else interesting pertaining to the adult coloration I found on bugguide.net: “Colors vary with overall temperature during pupation: if it was hot, the yellow/orange increases and the background becomes lighter, but if it was cold, the dark/black increases and the yellow/orange becomes darker like the background.”

Enjoy the last few days of sunshine and embrace our native pollinators. We are heading into the dark part of the year. For those of us who live here year round, you know what to expect. Lots and lots of rain.

Thanks for reading!

Western Calligrapher Fly (Toxomerus occidentalis)

Western Calligrapher Fly (Toxomerus occidentalis)

« Older Entries