The bane of fleas probably is not this plant

Species name: Erigeron strigosus

Common name: Plains fleabane, prairie fleabane

Location: Ontario

This plant is native to eastern North America, although it has naturalized itself to most disturbed prairie-type habitats across temperate North America. In fact, the genus Erigeron is most diverse in North America, with almost 175 species occurring here (or having evolved here). This species does well in moderately dry soils that can be periodically wet, and would typically be considered a "weed" since it likes to grow where you least want it. I wouldn't consider it invasive; it has a boom-and-bust style of population growth, but is a poor competitor for resources where there are other plants that occupy the same niche. It would likely be out-competed by other native species if challenged.

The common name for this plant comes from the idea that the dried plant repels fleas...I somehow doubt that's an effective plan for keeping fleas off your beloved pet. Erigeron as a group of plants are vitally important to some Lepidopteran (moths and butterflies) larvae, where some species of larvae must feed on one and only one species of Erigeron. Despite these plants not necessarily being the most attractive to the average gardener, a good diversity of native (to your area) Erigeron species is vital to a good butterfly garden!