Jan 072014

The extreme cold snap encompassing a large portion of continental North America (termed a Polar Vortex, which you can learn more about via NPR and Quartz) has made it dangerous to remain outside for long, even when bundled up in more layers than a Thanksgiving turducken. While we can rely on our technological ingenuity to find solutions to this chilling problem, what about our insect neighbours who have been left out in the cold?

Eurosta solidaginis has a warning for you.

Eurosta solidaginis has a warning for you.

Most insects seek shelter in the fall before temperatures begin to dip, either laying their eggs in sheltered locations, or hiding out as larvae, pupae or adults in the comparative warmths of the leaf litter, deep within trees, or even taking advantage of our warm hospitality and rooming with us in the nooks & crannies of our homes. But what about species like the Goldenrod Gall Fly (Eurosta solidaginis) which are literally left hanging out in the middle of nowhere and completely at the mercy of Jack Frost?

Polar Vortex vs. Goldenrod Gall Fly. Polar Vortex map courtesy of RightWeather.com, Eurosta solidaginis range map from Foote et al. 1993

Polar Vortex vs. Goldenrod Gall Fly. Polar Vortex map courtesy of RightWeather.com, Eurosta solidaginis range map from Foote et al. 1993

If you live in eastern North America, you’re probably familiar with the Goldenrod Gall Fly, even if you don’t realize it. This fruit fly — the ripe fruit kind (family Tephritidae), not the rotting banana kind (family Drosophilidae) — is one of the more ubiquitous insects, and is found pretty well anywhere goldenrod grows, including in urban environments like parks & abandoned lots. Adults are weak fliers and aren’t often seen unless you’re actively looking for them, but in this case, it’s the larvae that you’ve likely seen a hundred times — rather, you’ve likely seen their makeshift homes a hundred times. The larvae of this species live within the stem of goldenrod plants (Solidago spp.), and trick the plant into growing a big spherical nursery for the fly maggot to live & feed in (technically called a ‘gall’), and which stands out like the New Year’s Eve ball in Times Square, albeit without the mirrors and spotlights of course.

Goldenrod Gall Fly galls in Guelph, Ontario

Goldenrod Gall Fly galls in Guelph, Ontario

While these galls provide a modicum of protection from predators and parasitoids (although some still find a way), they don’t provide much, if any, insulation from the elements, meaning that the larvae must be able to survive the same air and windchill temperatures that we do. To do so, Goldenrod Gall Fly larvae are not only able to safely freeze without their cells being torn apart by tiny ice daggers by partially drying themselves out, but they also change the temperature their tissues freeze at by manufacturing anti-freeze-like chemicals. Together, these cold-tolerance strategies allow the maggots to survive temperatures as low as -50°C (-58°F)! Just take a moment to consider what it would feel like to stand outside almost anywhere in central North America on a day like today wrapped in only a few layers of tissue paper; BRRRRRRR!

All that stands between a Goldenrod Gall Fly maggot & the extreme cold is a few centimeters of dried plant tissue.

All that stands between a Goldenrod Gall Fly maggot & the extreme cold is a few centimeters of dried plant tissue. (The maggot is the little ball of goo in the bottom half of the gall)

For us, the multiple warm layers of clothing we bundle up in on days like today allow us to survive and eventually have children, thus passing our genes along, despite living in a habitat that is occasionally unfit for human life. It would stand to reason then that other organisms would also enjoy the same benefits and evolutionary advantage from thermal insulation, but, for the Goldenrod Gall Fly at least, the complete opposite is true! Goldenrod isn’t exactly the most robust structure, and it doesn’t take much effort from the wind, passing animals like people or dogs, or other not-so-freak phenomena to knock goldenrod stems over, allowing galls to be buried in snow and protected from the harshest temperatures (snow is an excellent insulator, and temperatures in the snowbank generally hover around 0°C (32°F)). This would intuitively seem like a good place to be if you were fly maggot, out of the daily temperature fluctuations and extreme cold and in a more stable environment. However it turns out that individuals that mature in galls on the ground and covered with snow are at a significant disadvantage evolutionarily speaking, with grounded females producing 18% fewer eggs than females who grew up fully exposed to the elements (Irwin & Lee, 2003)!

This Goldenrod Gall Fly, while warm(er), will likely produce fewer offspring when it emerges (assuming it's a female).

This Goldenrod Gall Fly, while warm(er), will likely produce fewer offspring when it emerges (assuming it’s a female).

Why might that be? Well, let’s think about it for a moment. If you’re a fly maggot hanging out above the snow when it’s -20°C, you’re likely going to be frozen solid and in a cold-induced stasis, not doing much of anything, even at the cellular level. But, if you’re as snug as a ‘bug’ under the snow at ~0°C, your body won’t be frozen, and thus you’ll be forced to carry on with day-to-day maintenance & cellular functions like breathing, waste removal, etc, even if only minimally. When you live in a closed system like a hollowed-out stem gall on a dead plant without any food, any energy you spend on daily functions as a “teenager” putting in time under the snow all winter long means you’ll have less energy you can put towards making eggs as an adult. If you’re a Goldenrod Gall Fly maggot, it pays to be left out in the cold!

Foote, R.H, Blanc, F.L., Norrbom, A.L. (1993). Handbook of the Fruit Flies (Diptera: Tephritidae) of America North of Mexico. Comstock Publishing Associates, Ithaca NY. 571pp.

Irwin J.T. & Lee, Jr R.E. (2003). Cold winter microenvironments conserve energy and improve overwintering survival and potential fecundity of the goldenrod gall fly, Eurosta solidaginis, Oikos, 100 (1) 71-78. DOI:

Some additional thoughts: You’d think that a nearly 20% difference in egg production would create significant evolutionary pressure for Goldenrod Gall Fly females to select the strongest, least-likely-to-break-and-fall-over goldenrod stems. It’s possible that the randomness of goldenrod stem breakage negates any evolution of host plant selection, but I would tend to doubt it. I did a quick Google Scholar search to check whether anyone had examined this in greater detail, but I didn’t see anything. Perhaps an avenue of future study for an evolutionary biology lab out there?

Nov 062013

There’s a pretty remarkable fly photograph making the rounds of social media today, and while it originally had me going “Oooooh!”, the more I think about it, the more I feel like we’re staring at clouds.

It started when Ziya Tong tweeted a photo of a Goniurellia tridens (a fruit fly in the family Tephritidae) displaying its wings:

Continue reading »

May 312012

I’m applying for a student fee waiver for this summer’s BugShot Insect Photography Workshop, and spent today putting together my image portfolio. After some ruthless culling and extra time spent with edits, I’ve arrived at 10 photos which I feel best represent my insect photography. Going through my photo library was an enlightening experience, and I’m quite happy with the progress I’ve made since my first attempts at macrophotography 5 years ago. Of course there’s still plenty of room for improvement (hence my hopeful application to learn from the masters), and there are a number of different techniques and ideas I want to play around with, so I don’t see myself running out of subjects or projects anytime soon!

Click the images to view at a larger size (650px long edge).

Apr 192012

After overwintering in a Ziploc bag stored in my barbecue, I was excited to see the first of my Eurosta solidaginis fruit flies (Tephritidae) had emerged from its puparium this morning! This was my first attempt at rearing Goldenrod Gall Flies, so I wasn’t sure what sort of success I was going to have, but so far, so good. Now to wait and see if I get any surprises!

Triumphant Eurosta solidaginis Tephritidae Goldenrod Gall Fly

Eurosta solidaginis (Tephritidae), the Goldenrod Gall Fly

Apr 112012

Urophora affinis Tephritidae Fruit Fly


Urophora affinis, a fruit fly in the family Tephritidae, was introduced to Ontario in the 1970’s as a biological control agent for invasive European knapweeds. When the researchers went back to check on the population a few years later, they were unable to find the species again, and concluded that the population failed to become established (at least in Ontario, a similar introduction in British Columbia did survive).

Fast forward to 2008 when Adam Brunke (a beetle specialist, ironically) collected a specimen in his parent’s backyard, nearly 200 kilometers away from the original introduction site! Clearly Urophora affinis had not only survived, but had even managed to expand it’s range across a large portion of central Ontario, a story which I reported in my paper on Ontario Tephritidae last spring.

Later on in the summer, I accompanied Adam and Steve Paiero (of tongue parasite fame) out to Northumberland County (much closer to the original introduction site) where they were conducting a survey, and happened to find a thriving population of Urophoa affinis in a nice sunny clearing. Nearly every composite flower had an individual or two on top feeding and/or mating, and we collected a long series to place in the University of Guelph Insect Collection. I also walked away with a number of nice photos documenting the species in a new location.

It just goes to show that a species can find a way to survive and prosper, even if they go unnoticed by us!


Jun 082011

With new identification aids, entomological collections begin to give up all manner of hidden treasures. The “Miscellaneous” drawers are no longer out of reach, and determining the species found in your own backyard (sometimes literally) can result in surprising finds.

Rhagoletis meigenii Tephritidae

Rhagoletis meigenii

Rhagoletis meigenii is an introduced species from Europe which infests fruits of European barberry (Barberis vulgaris) as larvae. This species had previously been recorded in North America as early as 1986, but after examining specimens from the Lyman Entomological Museum and here at the University of Guelph Insect Collection, I found specimens collected as early as 1956 in Montreal, Quebec and 1977 in Oakville, Ontario! This indicates that it had made it’s way to North America much earlier than previously thought, and either spread extremely rapidly across eastern North America, or had multiple introduction events! Luckily this species isn’t of economic concern (European barberry fruits are eaten and used in jams in Europe, but the plant harbours wheat rust and is considered noxious in North America), but it indicates how easily a non-native species can slip into a new area unnoticed by scientists and society.

Urophora affinis Tephritidae

Urophora affinis

Not all fruit flies enter North America “illegally” though. All three species of Urophora found in Ontario are native to Europe, but were intentionally introduced to help control unwanted, invasive knapweed species. Two of the species introduced became established and quickly spread through southern Ontario (Urophora cardui and Urophora quadrifasciata) while one species didn’t appear to survive. Urophora affinis was experimentally introduced in western Canada where it seemed to thrive, but after release in the early 1980’s at a research plot in Hastings County it failed to be found the next few years, leading the researcher to assume the population hadn’t survived the winter. But, a fly collected 250 km away and more than 20 years later in Simcoe County made it through the curatorial stream, and low-and-behold it was Urophora affinis! Apparently this species did in fact survive the winter, and managed to spread at low population density across central Ontario.


Rhagoletotrypeta rohweri Tephritidae

Rhagoletotrypeta rohweri

Finding flies thought to be gone is unfortunately not as unlikely as it may seem. Rhagoletotrypeta rohweri is a rarely collected species that hadn’t been seen since 1962. Or at least it hadn’t been thought to have been seen since then! The University of Guelph Insect Collection actually has 4 specimens collected between 1978 and 1985 around Point Pelee National Park. Hopefully this is evidence that this species is still clinging to existence in small pockets of eastern North America!



Rhagoletis chionanthi

Rhagoletis chionanthi

To round out some of the important species uncovered during this study, here’s Rhagoletis chionanthi. This species had previously only been recorded from North Carolina and Florida, making it’s presence in Ontario a significant expansion of its natural range! Of course this also begs the question as to what it’s using for a larval habitat; the only recorded host plant for R. chionanthi is Chionanthus virginicus (see what they did there, naming the species after its host? Crafty taxonomists…), a plant species which hasn’t been recorded from Canada yet! So what may be happening here? Has the plant expanded it’s range into Canada, bringing it’s pest with it? Or does Rhagoletis chionanthi have multiple hosts? Of course, the apple maggot fly, Rhagoletis pomonella, actually underwent a host-shift from hawthorn to apples when the latter were cultivated in North America, so perhaps Rhagoletis chionanthi has undergone a similar host-shift which we aren’t aware of!

Of course none of these records would have been possible without the entomological collections housed at universities or under provincial or federal care. At a time when taxonomy and natural history collections are devastatingly under funded (or threatened with military take-over), their intrinsic value is made clear through faunistic studies such as this. Who knows what other treasures are awaiting discovery in entomological collections, both large and small? New species await description, rare species make surprise appearances, and the dynamics between species and geography are unfolding with every study!

May 302011

Normally I’m pretty excited to see a new identification guide published in the Canadian Journal of Arthropod Identification; I get to see great images of insects I haven’t come across (yet), ID any of my photos which I couldn’t previously, and just have something new to read that I find especially interesting. The most recent publication is a little more exciting for me however, as I’m the lead author and it marks the culmination of several years work! W00t!

Without further ado, I present to you the Fruit Flies (Tephritidae) of Ontario! I’ll be going over the different aspects of the paper all this week; today focusing on the identification tools, Wednesday on a few of the important species, and Friday I’ll talk about how it’s relatively easy to contribute to CJAI!


Apple maggot fruit fly on apple with map of Ontario inscribed in it Continue reading »

May 242011

Ryan FleacrestIt was a great long weekend for us Canadians, with more than decent weather in my area, cold beer, and BBQ! I also came to the conclusion that I’m going to start referring to the holiday as Linneaus Day rather than Victoria Day; Linneaus contributed more to global society, considered himself royalty, and holds taxonomic priority – he was born in 1707 while Queen Victoria wasn’t born until 1819! But I digress…

Along with the great weather and beer, I’ve put the final touches on my first peer-reviewed journal article, which should be coming online sometime around lunch today! I’ll be blogging about it later on, but for now, here’s a song somewhat on topic by Nada Surf; Fruit Fly.



I’m pretty sure this song is referring to a family which are frequently called “fruit flies” but which I call “vinegar flies” – Drosophilidae. These diverse nuisances aren’t the same family as I’m publishing on, but the title “Fruit Fly” does fit my group, the Tephritidae. The closest I could come to finding a tephritid-relevant musical selection was the Seattle-area punk band Apple Maggot Quarantine Area, but they didn’t have any useful videos to share…

Anyways, keep an eye out later today for the full story!


This song is available on iTunes – Fruit Fly – Let Go