Mottled duskywing (Erynnis martialis)

Species Status: Endangered in Canada (COSEWIC assessment); Endangered in Ontario
Action Required: Population augmentation, reintroduction and/or assisted colonization

The plants that mottled duskywings feed on require dry sandy areas or limestone alvars found in very few places in eastern Canada. Unfortunately, these sensitive areas are also prime sites for human development.

The yellow-brown spots on the wings of this medium-sized butterfly give this endangered species its mottled appearance. Mottled duskywing larvae build silk leaf-nests, where they overwinter before emerging as adults between mid-May and late June. Males and females carry “scent scales,” which contain pheromones for attracting the opposite sex. Males are often found “puddling” — sipping water from moist soil to get salt and essential minerals. During mating, those nutrients are transferred to the female through the male’s sperm, which in turn improve the health of the female’s eggs.

Unlike many other butterflies that prefer lush meadows, mottled duskywings typically inhabit dry, partially shaded areas. These include sandy patches within woodlands, open barrens and places with shallow soil and sparse vegetation.

Historically, mottled duskywings could be found throughout the eastern and central U.S. and parts of south-central Canada. Unfortunately, their populations have plummeted to the point where they may have disappeared from many U.S. states in their core range. In Canada, these butterflies once extended into southwestern Quebec, southern Ontario and southeastern Manitoba. However, mottled duskywings have not been seen in Quebec since the 1950s, and in Ontario, they are only found in small, isolated populations. In Manitoba, they are limited to a small area of pine woodland in the southeast.

Habitat destruction and fragmentation caused by human development ranks as a primary threat to the mottled duskywing. Meanwhile, the plants these butterflies depend on are being eaten by deer and crowded out by invasive species. Spraying to control gypsy moth populations is also taking a toll on the mottled duskywing.

Recommended Recovery Actions

The Ontario Recovery Strategy for mottled duskywing calls for a number of conservation measures. These include mapping suitable habitat, protecting and managing habitat, analyzing the viability of current populations, and identifying the potential for augmenting existing populations, reintroducing populations to historical sites or assisting the colonization of new sites.

What we are doing

The mottled duskywing is on Wildlife Preservation Canada’s priority list for potential future action. Find out how we are currently saving other Canadian butterflies, such as the Taylor’s checkerspot and Karner blue, and how you can make a difference.