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Ontario Butterfly Atlas Online: Species Recoding Issues

Colin Jones, Ross Layberry and Alan Macnaughton

(link back to the main atlas page)


The Tiger Swallowtails


It has long been recognized that Ontario has two distinctive Tiger Swallowtails. In the southwest there has always been a large form, which has two generations per year, and in the rest of the province, a slightly smaller form which has only a single generation per year. These were clearly two forms of a single species, the Tiger Swallowtail, Papilio glaucus. In 1906 the northern form was named as a subspecies, Papilio glaucus canadensis. The southern form, by default, became known as Papilio glaucus glaucus. From the very first TEA Summary, in 1969, all records of these two subspecies were recorded separately.

In 1990 and 1991, several articles demonstrated that these two subspecies had different foodplants, and that each form’s preferred foodplants were toxic to the other. This was considered sufficient to divide the species into two, the Canadian Tiger Swallowtail, Papilio canadensis and the Eastern Tiger Swallowtail, Papilio glaucus. In 1992 Quimby Hess wrote a very informative article summing up the current literature on the subject. But in the Summary the two continued to be treated as subspecies until 1997. Finally, in 1998, they were treated as two separate species.

None of this really affected the identification of the swallowtails; in the southwest they were glaucus, elsewhere canadensis. But that changed as second generation specimens began to be seen on a regular basis in counties along the Lake Ontario shoreline east of Toronto, and to a much lesser degree, as far as Ottawa. There was no problem with the July and August specimens in any of these areas; they had to be glaucus.

The problem was what to do with May specimens. Most specimens can be positively identified by close examination, or possibly even with high-quality photography. But most records submitted to the TEA are sight records, and it is impossible to make more than a guess at the identity of a specimen as it flies by. So some observers began reporting their early-season records as “Papilio sp.”, ie a Tiger Swallowtail, but it could be either species. Further east, for example at Chaffeys Locks, Kingston or Ottawa, the number of July specimens is so low that it is reasonable to assume that May specimens are canadensis. But for Northumberland and Prince Edward counties, for example, a large proportion of these recent records have been left unmapped, because of this uncertainty regarding identification. They are included in the database, but with the comment “do not map, ID uncertain”.


Hess, Quimby, TEA Summary, 1992, pp:17-18



The Azure Complex, genus Celastrina


Twenty years ago we had just one species of Azure in Ontario: the Spring Azure, Celastrina ladon, which had two and occasionally three generations per year (and life was very much simpler!). Today we have three, and some problems remain in distinguishing them from each other. It is interesting to look at the history of the changes, and how they have been interpreted in the production of the TEA Interactive Maps.

Two articles, Pratt et al., 1994 and Wright, 1995 made a strong case for the existence of six species of Azure in North America. Three of these occurred in Canada, which prompted me to sum up their findings in Layberry, 1996. They proposed that what we had always known as the second generation of the Spring Azure was actually a different species, the Summer Azure, Celastrina neglecta; neglecta is an old name for a form of Spring Azure which was similar to our modern concept of the Summer Azure. The third species was just given a common name, the Cherry Gall Azure, because of its unique feeding habits; it eats the galls made by mites on the leaves of Choke and Black Cherry, and as such is partially carnivorous, for it eats the mites as well; it was not formally described until 2005, when it was given the name Celastrina serotina. This species was said to be very similar to the Spring Azure, but it flies a few weeks later, so fresh ones will be seen when most or all of the Spring Azures are very worn.

The immediate effect of this was that in the 1995 Summary, for the first time, the Summer Azure was listed as a distinct species; before that, all records from March to September were submitted and published as Spring Azures. In 1995 many July and August records were still published as the Spring Azure, in some cases as the neglecta form of the Spring Azure. The same situation occurred in 1996, with July records divided about equally between the two species. 1996 also marked the first Ontario record of the Cherry Gall Azure, a specimen reported on June 18 near Ottawa (Jeff Crolla), too late to have been a Spring Azure and too early for a Summer Azure. In 1997 almost all July specimens were listed as Summer Azures, but there were a few, then and in succeeding years, that still showed up in the Summaries as Spring Azures.

There were no more reports of the Cherry Gall Azure until 2001, when I reported a larva eating Cherry Galls, near Ottawa. There have been many other reports in the last ten years, mostly reports of the unmistakable larvae, but also some reports of fresh specimens which were seen in between the flight season of the other two species, mostly in June.

The final change came in 2008, when the species Celastrina ladon was divided into two, Pelham, 2008. Our northern subspecies of Celastrina ladon was declared to be a separate species, Celastrina lucia, with Celastrina ladon now occurring only in the US.

Our problem in preparing the data for the Interactive Maps was to separate records by date, but taking into account the vast size of Ontario, and the way this affects the timing of the flight seasons. We had to change the species name for many of the records, though always with a note listing the original submitted species names. We made a cut-off date for the Spring Azure, varying from very late May in the south to well into June, or even July in the north. Fortunately the Summer Azure does not occur over most of the north, so late records there had to be Spring Azures. And we made the starting date for the Summer Azure the very last few days of June, certainly accurate in the Ottawa area, and a little earlier than that in southern Ontario. This still left around 300 records submitted as the Spring Azure in June; undoubtedly some of these were unusually late Spring Azures, others were Cherry Gall Azures, and others were very early Summer Azures, but there was no way to know which was which; we had to list them as Celastrina sp., identity unconfirmed, and not map them at all.


Pratt, GF., D.M. Wright and H. Pavulaan, The various taxa and hosts of North American Celastrina (Lepidoptera, Lycaenidae). Proceedings of the American Entomological Society of Washington 96(3), 1994: pp 566-578

Wright, D.M., The American Azures: Our Blue Heaven. American Butterflies 3(1), 1995: pp. 20-28 and 30

Layberry, Ross A., The Spring Azure Species Complex, Toronto Entomologist’s Association Publication 28-96, Butterflies of Ontario & Summaries of Lepidoptera Encountered in Ontario in 1995, 1996: pp. 12-14

Pelham, Jonathan P., A Catalogue of the Butterflies of the United States and Canada, Journal of Research on the Lepidoptera, 40, 2008: pp 1-652.