Syrphidae | Bugging You From San Juan Island

Tag Archives: Syrphidae

Fantastic Fly Friday, Plum Tree Pollinators 🪰

Posted on March 27, 2026 by BUGGING YOU FROM San Juan Island One comment

It was 51 and sunny to partly cloudy yesterday afternoon about 4pm when I meandered down to our unkempt orchard to look for pollinators. The temps had dropped the night before to around 34-35, so you could say it is still pretty chilly here in the PNW on San Juan Island. At least it is in our neck of the woods.

We have a couple of Yellow Plum trees in bloom. Don’t ask me the species. I don’t know. I might get ONE or TWO plums a year if I get lucky. It’s not for lack of fruit. It’s my lack of ambition or desire to go down and collect them all and I am NEVER EVER peeling plums again to make jam or anything like that ever again in my life. The time I did, it took my wrists months and months to recover. Also, I just don’t want to be a homesteader. Don’t get me wrong, I love living on 7 acres, but it is not because I can have a garden. It’s largely because I didn’t want to have close neighbors. I won’t get into that here, but let me tell you that 7 acres is nowhere near large enough. You need a hundred, and your house needs to be in the middle.

So, what flies do I have to show you today? There were four species I counted, maybe five, but the fifth one was so tiny, I didn’t work on any identification for that one. There was only one solitary bee. I’ll point out here that there were ZERO honey bees. #1, it’s too cold, and #2 because they can’t fly in temps over 50, they are not going to be the ones pollinating your fruit trees. It’s largely flies, moths, and maybe some ants and beetles. Mostly it is flies.

(*Melanostoma mellinum)* Variable Duskyface Fly

Fly #1 The Variable Duskyface Fly (Melanostoma mellinum). This is a species of Syrphid Fly and I believe my specimen to be male. Syrphid flies are wonderful in gardens and orchards. They not only pollinate, but they scavenge aphids away in their larval form. Watch this one in action here

(Melanostoma mellinum) Variable Duskyface Fly

Fly #2 The Cluster Fly (Pollenia sp.) Pollenia flies have had some taxonomic revisions that I am not completely up to speed with, but suffice to say that they are now in their own family (Pollenidae) and I’ll attach some references at the end if you want to deep dive into the literature and try and figure out the species here.

What I can tell you about these flies is they got their name because they will sometimes overwinter in human structures (clustering). They are an Old World group, so these are not native to North America. They are parasites of earthworms, or at least one of the species in the Genus is. They also were ALL over the plum tree. I bet I counted fifty of these.

Fly #3, I believe this one (below) is the Greater Spring Blacklet (Cheilosia grossa), a species of Hoverfly in the family Syrphidae. This species is native to Europe and was introduced to the United States as a biocontrol for thistles. The adult is obviously enjoying its role as a plum tree pollinator and its offspring (the larvae) will help manage the thistles on our property, I suppose.

Fly #4 is Empis barbatoides, a Dance Fly. I had to stand on my tippy toes to try and get this video clip for you. I love this species of fly. They are so cool. The males catch other fly species, like March flies (Bibionidae) and make little balloon packets to woo a female. If you don’t believe me, you can read one of my earlier blog posts about them. I know a spot where the males seem to gather together to dance too. I keep hoping I’ll get some good video of them dancing to share.

And that’s all for tonight. It’s late and I’m going to bed. Just remember to repeat to your friends that FLIES are your friendly pollinators, and some of them are pest predators too. We need more people to advocate for them. They aren’t always a pest! 🪰

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

Brast, C. 2024. Dance With Me. Bugging You From San Juan Island. https://buggingyoufromsanjuanisland.com/2024/03/27/dance-with-me/

Bugguide. 2026. Cheilosia grossa. https://www.bugguide.net/node/view/1032753

Bugguide. 2026. Melanostoma mellinum. https://www.bugguide.net/node/view/36894

Gisondi S, Rognes K, Badano D, Pape T, Cerretti P (2020) The world Polleniidae (Diptera, Oestroidea): key to genera and checklist of species. ZooKeys 971: 105-155. https://doi.org/10.3897/zookeys.971.51283

Jewiss-Gaines, A., Marshall, S.A., Whitworth, T.L. 2012. Cluster flies (Calliphoridae: Polleniinae: Pollenia) of North America. Canadian Journal of Arthropod Identification No. 19, 15 February 2012, available online at doi: 10.3752/cjai.2012.19

Fantastic Fly Friday

Posted on April 11, 2025 by BUGGING YOU FROM San Juan Island Leave a comment

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.

Golden Dung Fly (*Scathophaga stercoraria*)

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

Diptera

Western Calligrapher (Toxomerus occidentalis)

Posted on October 18, 2022 by BUGGING YOU FROM San Juan Island Leave a comment

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!