Tag Archives: Robber fly

Identifying the Nicocles canadensis Robber Fly

Posted on by Leave a comment
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!

Nicocles sp. Robber Fly
Nicocles sp. Robber Fly
Nicocles sp. Robber Fly
Nicocles sp. Robber Fly
Nicocles sp. Robber Fly
Nicocles sp. Robber Fly

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

Know Your Pest Predators – Make Friends with Eudioctria sackeni

Posted on by One comment
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 sackeni Robber Fly
Eudioctria sackeni Robber Fly
Eudioctria sackeni Robber Fly
Eudioctria sackeni Robber Fly
Eudioctria sackeni Robber Fly
Eudioctria sackeni Robber Fly

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

Bug Diary for October 6, 2022 ~ Metellina Spiders Share a Lunch Wrap, an Unusual Fly, Two Wandering Caterpillars, and “One- Eyed Wanda” Gets Rescued By a Seeing-Eye 👀Human.

Posted on by Leave a comment

I was eating my lunch outdoors yesterday (October 6, 2022), and considering the end of season, depauperate community of bugs. There are fewer and fewer buzzing about the lingering tiny blossoms on my mint plants, which have been well-visited this season. Many of the winged flyers die out on their own accord. Lives spent – an ending synchronized with leaves falling from the trees. They’ve lived a season, maybe longer depending on the species. As adults, they’ve mated and sewn seeds for a new generation to emerge in spring. Some though, are captured and eaten by other organisms that are fueling stores for their own reproductive event – like these Long-jawed orb weaver spiders (Metallina segmentata) I witnessed, working together to wrap up their “lunch,” a Thick-legged Hoverfly (Syritta pipiens).

Metellina segmentata spiders (male and female) with lunch (Syritta pipiens) hoverfly
Long Jawed Orb Weavers (Metellina segmentata) with prey, a Thick-Legged Hoverfly (Syritta pipiens)

I didn’t realize it at the time, but depauperate was not to be the theme of my day!

Shortly after observing and filming the spiders, I noted some buzzing around our fruitless cherry tree. I walked over, thinking to myself, “You’re getting too close to that Yellowjacket!” Well, it wasn’t a yellowjacket at all. It was a Robberfly (Laphria ventralis), I believe – and SHE was ovipositing into our tree.

Laphria ventralis Robber Fly – 10.6.22, San Juan Island, WA

Later this evening when I was showing my husband the photos, he asked what the eggs would eat when they hatch. I had to look it up. Well, Robber Fly larvae are known to prey on the eggs, larvae, and pupae of other insects, especially beetle larvae living in decaying trees. Read more about this linked here: https://www.geller-grimm.de/genera07.htm

This Robber fly was an incredible mimic of a Yellowjacket – not only in appearance, but also in the way she flew about the tree. Fascinated, I watched her find a niche under some old bark and begin to oviposit. She did not like my camera or my presence, but tolerated me to a degree. Then she buzzed right into my face with complete confidence her mimicry would chase me away. Guess what? It worked. At least temporarily.

Laphria ventralis Robber fly ovipositing 10.06.22 – San Juan Island, WA
Laphria ventralis 10.6.22 San Juan Island, WA
Buzz Off! Laphria ventralis Robber Fly 10.6.22

The next fun finds in Bug-landia were two caterpillars. I found an Eyed Sphinx Moth caterpillar (Smerinthus opthalmica) making headway down our driveway, undoubtedly wandering off to find a suitable location to pupate.

Smerinthus opthalmica (Eyed Sphinx Moth caterpillar) 10.6.22

The second caterpillar I found is my absolute favorite moth species, the Rosy Aemilia moth (Lophocampa roseata). Since it was navigating down the middle of the road, I did gently relocate it to a safer spot so it wouldn’t get smooshed by the giant gravel trucks that fly up and down our once quiet country road.

Lophocampa roseata, the Rosy Amelia Moth caterpillar

Last, but not least is my new “pet.” I found her on my walk and she needed some help, so she’s come home to stay with us for some R&R, and a bit of end of life care. I’ve named her Wanda… One-Eyed Wanda. Wanda had evidently become an assault victim sometime just before I found her. The thought is that she was attacked and bitten by another female mantis – who evidently fled the scene before I got there. Poor wounded Wanda was not in great shape when I picked her up. She is missing an eye. It was not a pretty sight, but I couldn’t just leave her in the road.

Mantis religiosa (European mantis) and, “One-eyed Wanda”

She’s hanging out in the dining room tonight in a bug habitat/safe room so my indoor cats don’t batter her. I think she’s had enough battering in this life. I’m hoping she will still be able to lay an egg sack for me before she expires. Definitely plan to try and feed her tomorrow. I doctored her eye as best as I could. She can still see with the other one. Poor Wanda. 😦

Next up – Look for my post and forthcoming PowerPoint slide show about What’s Bugging Gary! Even better, check out the event (Garry Oak Conservation Symposium) in person if you’re on San Juan Island. It’s this Sunday at the Grange.

References and More Good Stuff to Check Out

Brast, C.L. 2018. Lophocampa roseata (ROSY AEMILIA). Bugging You From San Juan Island. https://buggingyoufromsanjuanisland.com/2018/10/02/lophocampa-roseata-rosy-aemilia/

Bugguide.net. 2022. Lophocampa roseata. https://bugguide.net/node/view/247272

Bugguide.net. 2022. Metellina segmentata. https://bugguide.net/node/view/153661

Cannings, R. A. 2014. The Robber Flies (Diptera: Asilidae) of Western Canadian Grasslands. Chapter 7.10.3752/9780968932179. http://staff.royalbcmuseum.bc.ca/wp-content/uploads/2014/06/Cannings-Asilidae-BSC-003-Vol4-Ch7-2014-.pdf

Cannings, R.A. 2007. Recent range expansion of the Praying Mantis, Mantis religiosa Linnaeus (Mantodeaz Mantidae), in British Columbia. Journal of the Entomological Society of British Columbia, 104, 73-80. https://journal.entsocbc.ca/index.php/journal/article/view/101

Geller-Grimm, F. Information on Robber Flies. https://www.geller-grimm.de/genera07.htm

McAtee, W.L. 1918. Key to the Nearctic Species of the Genus Laphria (Diptera, Asilidae). The Ohio Journal of Science. v19 n2 (December, 1918), 143-172. https://kb.osu.edu/handle/1811/2019

Nelson, D. 2022 Laphria Ventralis. 10,000 Things of the Pacific Northwest. Adventures of a Recreation Naturalist. http://10000thingsofthepnw.com/2021/07/31/laphria-ventralis/

Nelson, D. 2022. Metellina segmentata. 10,000 Things of the Pacific Northwest. Adventures of a Recreation Naturalist. http://10000thingsofthepnw.com/2020/10/25/metellina-segmentata/

Nelson, D. 2022. Smerinthus opthalmica. 10,000 Things of the Pacific Northwest. Adventures of a Recreation Naturalist. http://10000thingsofthepnw.com/2022/06/27/smerinthus-opthalmica/

PNW Moths. 2022. Lophocampa roseata. http://pnwmoths.biol.wwu.edu/browse/family-erebidae/subfamily-arctiinae/tribe-arctiini/lophocampa/lophocampa-roseata/

PNW Moths. 2022. Smerinthus opthalmica. http://pnwmoths.biol.wwu.edu/browse/family-sphingidae/subfamily-smerinthinae/smerinthus/smerinthus-ophthalmica/

Thanks for Reading! 🐛