Syrphidae | Bugging You From San Juan Island

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*)

(*Melanostoma mellinum* )Variable Duskyface 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

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!