This afternoon I would rate a 10/10 for entomological adventure. It happened outside, just behind our barn about 3:30pm. I went out to feed our resident raven and took a stroll over to a sunny corner of our property. As I neared an old barbed wire fence line, I noticed an aggregation of flies bobbing around over one of the native Ocean Spray (Holodiscus discolor) shrubs. Moving closer, as stealthily as possible, I saw these were Empis dance flies and I got very excited. There seemed to be about 15-20 in the group.
Empis Dance Fly (male) with Bibionid fly nuptial gift
I watched as I stood in the sun. The sun’s warmth felt really good on my body. Hopefully, we will have more sunshine and some days of vitamin D will infuse my cells and pull me out of this funk I have been wallowing in. The flies dancing in the sun were a sight. I crept forward a bit closer, trying not to slip into the fencing, but enough so as to get some video to share.
You will have to forgive me for the shake in the footage. It is not easy to remain steady and focus on a nervous fly that leaves its perch if you so much as breathe too deeply when you are moving the camera close enough to zoom in for a good macro shot. I think I was holding my breath a lot while I was trying to take pictures.
Empis Dance Fly with nuptial offering
This fly should be classified in the genus Empis. Last year, I found Empis barbatoides in our orchard. You can read an earlier blog post I wrote about them here https://buggingyoufromsanjuanisland.com/category/dance-fly/empis-barbatoides/ I believe these may be the same species, but I say this with a caveat. I am hoping to get my hands on a copy of the revisions by Sinclair, Brooks, and Cumming I have referenced below. It appears I may need this and the updated keys to try and ID my fly beyond genus level, so I’ve emailed the lead author and hopefully will hear something back.
If you look closely, you’ll see in some of the photos the fly is holding a balled up insect. This is a species of March fly in the family Bibionidae. I saw a few hiding around in the tall grass like this one in the photo below.
March fly (Bibionidae) hiding in the grass
Evidently, they were being picked out by the male flies and rolled up into a nice nuptial gift to present to a female Empis fly to entice her to mate. The male Empis fly will carry this balled up dead insect and “dance” around to attract a female. That’s what I found so fascinating to actually watch in person. It isn’t every day you see something like this! Since flies seem to be attracted to certain spots for mating aggregations (it’s called hilltopping), perhaps this is a spot where I might be lucky enough to see this action again.
References and Further Reading:
Alcock , John. 1973. The mating behaviour of Empis barbatoides Melander and Empis poplitea Loew (Diptera: Empididae), Journal of Natural History, 7:4, 411-420, DOI: 10.1080/00222937300770301
Sinclair BJ, Brooks SE, Cumming JM. Revision of the western Nearctic species of Empis subgenus Enoplempis (Diptera: Empididae). Zootaxa. 2025 Mar 31;5615(1):1-200. doi: 10.11646/zootaxa.5615.1.1. PMID: 40173481. https://pubmed.ncbi.nlm.nih.gov/40173481/
I had an amazing BUG day! It’s always amazing when you find one as interesting as this one. Check out the proboscis.
This is Empis barbatoides, I believe, a species of Dance fly in the family Empididae. SHE (you can see her ovipositor at the end), was in the back of my truck on some cardboard I am using for landscaping.
I find the behavior of these flies to be so interesting. When they are in mating swarms, the male flies will dance about to entice the female. The most fascinating part is they often are carrying a captured insect, usually a Bibionid fly, wrapped in silk, as an offering or nuptial gift.
Females seem to prefer a male with the most enticing balloon. Some males only carry an empty ball of silk. My guess is they get whoever is leftover. 😉
These flies and their developing larvae are found in moist wooded habitats (mixed deciduous and coniferous) with many clearings and open patches.
Larvae are often in decaying vegetation, or even under the bark of trees.
Adult flies are approx 9-10mm
For some fantastic (not mine) photos of the males carrying balloons, check out the bugguide link below.
References
Alcock , John. 1973. The mating behaviour of Empis barbatoides Melander and Empis poplitea Loew (Diptera: Empididae), Journal of Natural History, 7:4, 411-420, DOI: 10.1080/00222937300770301
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
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
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.
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 DaffodilRhamphomyia 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:
Rhamphomyia Dagger Fly in DaffodilRhamphomyia Dagger Fly in DaffodilRhamphomyia Dagger Fly in DaffodilRhamphomyia Dagger Fly on DaffodilRhamphomyia Dagger Fly on DaffodilRhamphomyia Dagger Fly on DaffodilDeceasedRhamphomyia Dagger Fly in DaffodilDeceasedRhamphomyia Dagger Fly in DaffodilDeceased Dagger fly under microscopeDeceased Dagger fly under microscopeDeceased Dagger fly under microscope
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 Behav29, 153–161 (2016). https://doi.org/10.1007/s10905-016-9545-5
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
Bugging You From San Juan Island 