In the 1970s, migratory coccinellid aggregations on western Lake Superior shorelines consisted of over 90% Hippodamia convergens Guérin-Méneville. In 2014, the alien Harmonia axyridis (Pallas) accounted for over 80% of shoreline coccinellid aggregations and H. convergens declined to less than 10% of the total. Additional work is needed to elucidate the extent and cause of the decline of H. convergens in western Lake Superior shoreline aggregations.
Steffens, Wayne P. and Lumen, Ryan P.
"Decline in Relative Abundance of Hippodamia convergens (Coleoptera: Coccinellidae) in Fall Shoreline Aggregations on Western Lake Superior,"
The Great Lakes Entomologist: Vol. 48
, Article 8.
Available at: http://scholar.valpo.edu/tgle/vol48/iss3/8