An Invasive Moth is Recorded in Ontario, Canada for the First Time - Observation of the Week, 9/9/18

This Box Tree Moth, seen in Ontario, Canada by @kyukich is our Observation of the Week!

As our world becomes more interconnected through commerce and transportation, the likelihood of organisms native to one region of the planet being transported another region has of course increased, and the Box Tree Moth (Cydalima perspectalis) is an example of how quickly this can happen.

Originally hailing from eastern Asia, caterpillars of the Box Tree Moth host on plants of the genus Buxus, which are often used in for hedges and topiaries. In 2006 or 2007 its first European sightings were in Germany, likely brought in on Box Trees shipped from China. By 2010 it had caused severe defoliation (with many fully defoliated plants dying) of the country’s largest Buxus forest in the Grenzarch-Whylen Nature Reserve. It has spread to much of Europe and Britain and is also established in Sochi, Russia when it was likely imported with topiary plants for the 2014 Olympic Games. While some wasps and flies are known to parasitize Box Tree Moths in their native habitats, very little is known about them, and the larvae seem to be distasteful to birds often being found regurgitated or not eaten.

The moth has not made a splash in the Americas, but several specimens were found in Ontario, Canada in late August of 2018, including the one photographed above, by Karen Yukich. Karen has been an iNaturalist user since 2016 and says “I don’t get into fine points of anatomy or capture insects for close study – my forte is to keep an eye out for small creatures on vegetation and then try to quickly get a decent ID shot.

That was what happened on the morning of August 25 this year. When I returned home late morning, I paused before entering our walkway to check our small wild pollinator garden. Sometimes if I go too fast I scare away something interesting, so I’ve learned to check first. This time I saw what looked like a Melonworm Moth (Diaphania hyalinata), a species I’ve seen in south Texas, fluttering inside the Indian hemp...So I carefully snuck past to get my long-zoom camera (Lumix FZ60), and then took a few shots while it moved over to our neighbour’s ornamental shrubs. It soon disappeared into their overgrown boxwood hedge.

After looking at her photos, Karen realized this she was not familiar with this particular moth, so she called her friend Dave Beadle (@dbeadle), co-author of The Peterson Field Guide to the Moths of Northeastern North America and manager of Ontario Moths. Dave tells me,

It all came as a bit of a surprise really. Karen phoned me to say she’d photographed a strange moth and had put it in iNat if I’d care to have a look. By the time I checked it out it had already been correctly identified by Karen and confirmed. I was amazed since this species was not really on my radar to occur in Ontario. I knew that this East Asian native had become rather widespread across much of Western Europe as an adventive species, but didn’t really think of it making it this far!

Another observation of a Box Tree Moth in the Toronto area was also posted in a local Facebook group, and just a few days later Dave himself found one (photo below) in his backyard moth trap, explaining “I knew exactly what it was before I even opened the trap!”

Mike Burrell (@mikeburrell), a Project Zoologist for the Ontario Natural Heritage Information Centre (NHIC), tells me “[these look like] like the first records for Canada...This is certainly a great example of Citizen Science for early detection of exotic species.” 

It will take some more digging to see if these are the first sightings for all of North America, but so far I haven’t been able to find any other North American records on either iNaturalist or Butterflies and Moths of North America, so it’s possible they are among the first for the continent. Dave Beadle explains, “I suspect it has the potential to become more common and widespread in Ontario, wherever its larval food plant occurs. This, of course, rather depends upon whether the eggs/larvae can survive the Ontario winters. If it made it into the southern United States it probably would not have a problem surviving the winter.”

Karen (above, in Manizales, Colombia) is not only a backyard naturalist. She volunteers at High Park Nature and helps coordinate the High Park Moth Night, which is co-sponsored by the High Park Nature Centre and the Toronto Entomologists’ Association. It was actually through High Park Nature that she met David Kaposi (@dkaposi), who introduced her to iNaturalist (and alerted me to this finding). Interestingly, she got into nature after her husband, Bob, bought her a field guide for birds in 1980. “I didn’t use it but he got hooked!” she says. “Birding became a big part of his life and we both learned a lot more about nature. We started taking nature trips to local sites and then to the neotropics. In the mid-90s he became similarly passionate about butterflies, and I would photograph some of them with my old SLR camera. After we both moved into digital cameras, Bob became the more serious butterfly photographer and I began to pay more attention to other insects.”

She has embraced iNaturalist and says

I’ve found [it] very useful for identifying species in our region, and especially useful for insects I photograph on our winter trips to Central and South America, for which reference sources are hard to find. Leafhoppers and other true bugs are my particular favorites, but I look out for all kinds of creatures, especially the tiny ones that others may not notice. It’s like finding a secret little gem! And then being able to share my sightings with others and to contribute as a citizen scientist via iNaturalist adds a whole new dimension!

- by Tony Iwane. Photo of Karen Yukich by Bob Yukich.

- Over 2,000 observations have been recorded for the High Park Moth Study project on iNaturalist! 

- And the Moths of Ontario project on iNaturalist has nearly 62,000 observations of over 2,000 species!

- Mike Burrell has helped to create and manage the NHIC Rare species of Ontario project and iNaturalist users have recorded over 15,000 observations of nearly 1,000 rare species!

- The European Boxwood and Topiary Society has a great page detailing the Box Tree Moth and its spread in Europe.

- Check out this time lapse of Box Tree Moth caterpillars going to town on a plant. 

Posted on September 09, 2018 09:06 PM by tiwane tiwane


Spectacular observation @kyukich! Some really interesting stuff being documented in and around Ontario -- really enjoy watching those observations come in. Keep it up!

Posted by sambiology about 5 years ago

Someone found one in Toronto, eh? I'm pretty close to there. A lot of moths like to rest in a tunnel near my house (, maybe I'll find one there. I'll be sure to keep a look out.

Posted by mws about 5 years ago


Posted by diegoalmendras about 5 years ago

Very cool finds!

Posted by susanhewitt about 5 years ago


Posted by sea-kangaroo about 5 years ago

From the limited research I've done, I don't think it could survive a 'real' winter (ie. Winnipeg) as opposed to a Toronto winter (for non Canadians, it's a long running joke). Seems like it is restricted to more temperate areas, though it might migrate ( ). We've recently found the Emerald Ash Borer here, so another invasive species would be a bit much. Though I don't even know if Boxus spp live here.

Posted by mamestraconfigurata about 5 years ago

It's always exciting to see a new species. I remember my first sighting of the Box Tree Moth this year in Austria, where I live (which posted to iNat, of course). However, it has been decimating the boxwood trees here, including the ones in my yard and those of my friends and neighbors. Since I disposed of our boxwoods, the moths have been hanging around our butterfly bush (Buddleja). This reminds me of other entire tree species being decimated by other invasive species in North America. I hope the same thing doesn't happen to boxwoods in North America, but I am pessimistic on this point. However, I agree that iNat is invaluable in early detection of such species. Maybe it will help in this case.

Posted by dellfalconer about 5 years ago

Yes, definitely a pest animal, as it caused the loss of lots of box trees in my home Styria, Austria. Cydalima perspectalis causes a lot of effort and costs to protect planted box trees here. For sure this is my job as well, still i wished we could get rid of this damaging invador.
Please be aware, this moth will have the potential to spread in southern Ontario, at least where the food plant is frequently grown. Better to get rid of as soon as possible than to get much damage!

Posted by erwin_pteridophilos about 5 years ago

Another example of early detection: is a Leaf beetle species native to, and common in Europe.

We have two sightings from NE N-America (Nova Scotia 2011, Vermont this year), and it also seems not officially recorded. The species, other than the Box tree moth, will not cause trouble, but rather become beneficial, because its foodplant is an invasive herb (Galeopsis tetrahit).

Posted by borisb about 5 years ago

Is this the same species known as the brown tail moth spotted in Maine?

Posted by harlandalpaugh about 5 years ago

@harlandalpaugh no, this is another kind of moth, feeding solely on some kinds of box trees (resp. shrubs), Buxus sp., which are alien to North America. Box tree moth, Cydalima perspectalis is not known to cause any harm to humans, other than Brown-tail moth, Euproctis chrysorrhoea in Maine or elsewhere.

Posted by erwin_pteridophilos about 5 years ago

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