About the Ontario Butterfly Atlas

..maps...display of records...flight season charts


The Ontario Butterfly Atlas is a project of the Toronto Entomologists' Association. The TEA has been accumulating records and publishing annual seasonal summaries (Ontario Lepidoptera) for 50 years, with the first edition appearing in 1969. The first maps appeared in the TEA's Ontario Butterfly Atlas book, published in 1991. The present interactive web-based maps started in 2011. Since that time, the database of records supporting the maps has grown from 65,000 in 2011 to almost 440,000 today. The latest update was in February 2020.


Atlas data comes from eButterfly records, iNaturalist records, BAMONA records, and records submitted directly to the TEA. Some data is from other sources (e.g., ROM, other museums, BOLD). Data from all TEA seasonal summaries is included. The atlas is updated at least once a year.


In 2019, 37,000 records were added to the atlas. The sources of 2019 atlas records were: 39% from iNaturalist; 35% from eButterfly; 25% from direct submissions of records on spreadsheets to the TEA; and 1% from BAMONA. Direct submission had been the top source of records until eButterfly came on the scene. eButterfly was the top source of records in 2017 and 2018, but iNaturalist took over the top spot in 2019. For more details on sources of data, and their pattern over time, see this table.


We thank Bird Studies Canada for providing the shape files defining the 10,747 10 km squares shown on these maps. The shape files for counties and parks are from Ontario's Land Information Office and contain information licenced under the Open Government Licence - Ontario.

Other Canadian butterfly atlases: the Maritimes Butterfly Atlas and the TEA'sPrairie Provinces Butterfly Atlas. See also the TEA's Ontario Moth Atlas.


There will be inevitably be some errors or questionable observations, and we would like to know about this. We also welcome any questions about the atlas or suggestions for improving it. Contact the TEA (Alan Macnaughton, info@ontarioinsects.org).


In publications or other research use of this data, use the following citation: Alan Macnaughton, Ross Layberry, Rick Cavasin, Bev Edwards and Colin Jones. Ontario Butterfly Atlas (Supply date accessed here).



Table of new county records (2019 and previous years)
- but if you are interested in a particular county, see this table instead

Table of new birding-square records (2019 and previous years)