"If you spot a spotless lady beetle in Ontario, at least if it is under 6 mm, it is likely to be the only species of Cycloneda, C. munda. Similarly immaculate Harmonia axyridis specimens occasionally occur, but they are much larger (8mm or more), and usually have a white M-shape on the pronotum (right behind the head) rather than the white-edged pronotum of Cycloneda."
