Giant Swallowtail Butterfly Invades Ontario

Photo of Giant Swallowtail May 2012 Near Sharbot Lake OntarioChrome yellow Tiger Swallowtails and purply Black Swallowtails are welcomed each year in southern Ontario. However, this spring another swallowtail flitted into the flowers in the mixed forest north of Kingston, Ontario. With wings that would span a slice of bread, and sporting a vivid triangle of thick yellow lines on an almost black background, it was unmistakably a Giant Swallowtail. To prove it wasn’t a fluke, several more arrived moments later.

Mild Winter and Warm Dry Spring Propel Butterfly Invasion Into Ontario
A few weeks earlier, record numbers of Red Admirals had fluttered into Ontario. Homeowners were astonished to count 50, 100, even several hundred Red Admirals hovering around blossoming trees sipping spring nectar.

This combination of temperate weather probably also promoted the conditions necessary for these Giant Swallowtails (Papilio cresphontes) to stretch north beyond their normal limits so early in the season.

Photo of Giant Swallowtail and Begonia near Sharbot Lake OntarioIs There Anything to Eat Around Here?
Luckily for these adventurous Giants, the spring lilacs were blooming. They tanked up on nectar to keep fueled up for the cool nights.

Later in the summer, they were investigating all the flowers both wild and domestic. In this photo, one was checking out the non-stop begonias.

Will They Lay Eggs Here?
This is a question I’m still puzzling over. The Kaufman guide suggests Giant Swallowtails prefer citrus for their larvae. Despite the warmer winters, orange trees are still in short supply in south-eastern Ontario! Other suggested host plants (torch wood, wild lime and hopwood) also don’t seem likely.

Photo of Giant Swallowtail May 2012 Near Sharbot Lake OntarioIn the Point Pelee Ontario region caterpillars do successfully feed on Hop tree and Northern Prickly Ash. Prickly Ash apparently is a member of the citrus family, not the ash family. So the Giants can likely reproduce at least as far north as the Prickly Ash grow.

Where there are no suitable hosts for the caterpillars, our only hope of admiring these gentle Giants will be when mature adults decide to push the boundaries of their range with a little cross-border fluttering.

Join in
Have you seen Giant Swallowtails in your neighbourhood? Or are the Tigers and Blacks more common? Share your views and news with a Comment.

Further Reading
Butterflies of Canada

Toronto Star article: Species Migrating North at ‘Two and Three Times Faster’ Than Reported at–species-migrating-no

In the Ottawa Citizen “Giant butterfly makes ‘astonishing’ Ottawa debut”

Related Reading

36 thoughts on “Giant Swallowtail Butterfly Invades Ontario

  1. Didn’t know what this giant butterfly. Thank you for helping me identify the swallowtail Was settled with wings open on our Spirea in our Markham garden today.

    • They are still quite new to southern Ontario. We were quite surprised with our first glimpse of one too. They have become residents in some parts of Ontario now, so with luck you’ll see them again next summer.

      Thanks for sharing your sighting!

    • Found five Swallowtail caterpillars devouring my parsley plant this morning in Markham. What should I do with them?

      • Well, personally I would let them continue as I can buy parsley but I can’t buy Swallowtails. However, other choices include moving them onto carrot or Queen Anne’s Lace leaves, if there are some nearby, if they seem to be eating too much of your parsley. Hopefully there is some Queen Anne’s Lace in a nearby park if you don’t have a large vegetable garden.

  2. August 15, 2014
    A giant swallowtail spent a long period of time today on our butterfly bush. Beautiful. We live on the Bateau channel eastern end of Lake Ontario. First one that we have seen.

    • They’re lovely butterflies. Hopefully you have a few this year that will survive the winter to start a new resident population.

      Thanks for sharing your sighting!

  3. Had a Giant Swallowtail on our cosmos flowers in Brighton this morning. Had never seen one before. Got a great pic to show friends.

    • Congratulations on getting a photo! They often stay in flight while feeding which can make it difficult.

      It seems like a good year for these butterflies. People are seeing them all across southern Ontario.

      Thanks for sharing your experience!

      • Hello Bet
        Do you know when the giant swallowtail emerges from the chrysalis in the spring in southern Ontario
        Thank you

        • Unfortunately, I don’t.

 has flight times for Ontario from mid-May on but that may include mature Swallowtails that flew up from the USA.

          Similarly, the ROM Field Guide to Butterflies of Ontario lists flight times from mid-May till the beginning of October with peaks from mid-May to mid-June and again from late July through August. It doesn’t state whether those peaks correspond to migrants or local hatches, though.

          If another reader has experience with Swallowtails over-wintering in their area, please chime in and let us know!

  4. We just spotted a Giant Swallow a Tail in our garden. It was feeding on the Cone Flower. We have been watching it for about 15 min. Absolutely beautiful.(Brantford Ont.)

  5. My wife and I watched a Giant Swallowtail circle and momentarily land on our mature Hop tree yesterday. It did this for hours. Finally it flew away at which time I looked closely at the leaves. My tree is covered in tiny reddish yellow eggs!!! All on the top side of the newest growth of leaves. I live in southeast Scarborough.

    • Thank you for sharing this! I knew they must be finding somewhere to lay their eggs but I wasn’t sure how many host plants they could find in Ontario. Hopefully some of the eggs will hatch in time to pupate before the fall. Keep us posted if you see any caterpillars. (I’m not even sure what the caterpillars look like; I guess I should go look them up.)

      Thanks again!

  6. August 27 2014
    11:00 am 6 km north of Bridgenorth Ontario Chemong Lake – Took pics with I phone of giant swallowtail flitting from a hummingbird feeder to a cluster of Cleome flower to a pot of Diplodenias. It was the most beautiful thing I have ever seen!!

  7. I saw the giant black swallowtail on Thurs. Aug. 13, 2015. I have a beautiful photo but your website does not allow me to attach it. The markings look like the open jaw of a skull. How did this species acquire such camoflage?!

    • I’m happy to hear you were able to get a great photo of one of these large swallowtails. The markings are quite showy. Thanks for sharing your sighting!

  8. We have 7 caterpillars on our tiny hop tree in Ridgetown, Ontario – just planted it last year. I’m hoping they survive the winter!

      • They ate on my hop tree for a few days. I was watching carefully because I wasn’t sure my tiny tree could support them all. Then over a few days they disappered. I saw one heading down the trunk, so I don’t think they were eaten. They seem to have moved elsewhere. I guess I’ll have to wait until spring to see if any butterflies appear.

  9. Prickly Ash, though a native, has w/in the past decade become invasive on much farm scrubland (and along fencelines) in Lanark country. I would love to know why it is suddenly booming (it’s a significant problem locally) — but that it is, is clearly of signif bonus for the increasing Giant Swallowtails.

    • Interesting that it’s spreading so aggressively. Cow Parsnip is doing that quite a few places too. Yes, I’m sure the Giants are pleased. If I see any info about the spread of Prickly Ash, I’ll post a link, but I haven’t seen anything yet. Thanks for sharing your sighting!

  10. We have been raising Giants on Rue in our yard in St Catharines Ontario for about 6 years now

  11. I have citrus trees (bushes, really) in pots that I put out on my porch for the summer. There are two Giant Swallowtail caterpillars on them again this year devouring the leaves.

  12. Just saw one of these in my back yard in east-end Toronto. Really cool! It seems slow and is not flying much tho. Just hopping around a bit. Wondering if it’s dying? 🙁

    • It may be just about done as they do just hatch out, reproduce, and then die. Or it could be that it was a cold day (strange summer!) which makes it harder for them. Unfortunately, there are also diseases and mini-predators that can kill them. Hopefully it helped start to create the next generation!

  13. Saw a Giant Swallowtail in Toronto (near Yonge and Davisville) this morning on our buddleia (butterfly bush) August 29, 2017, got a nice video. Probably 5-6 inches wingspan. Not sure if male or female.

    • It’s turning into a great summer for these Giants. Thanks for sharing your sighting–and for offering the butterflies a place to rest and get a drink!

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