Dear Wood Folk,
Silvery blue (glaucopsyche lygdamus) butterflies are easily mistaken for similarly blue azures, who were featured in our diaries earlier this year. I almost included the silvery blue caterpillar (below in this feature) in the azure diary by mistake!
The slivery blue are easier to find with their wings spread open than azures. They’re also easier to approach. You don’t have to sneak like you do with azures!
You may spot them in busy grassy meadows, roadsides, trail sides and open areas within the woods. When you see the vetches blooming, start looking!
Silvery Blue Plant Allies
In Ontario, sundial lupine is the main native plant host of silvery blues. Unfortunately, a handful of vetches and other pea family nonnatives, like alfalfa, have been introduced to Ontario in crop cover and soil erosion mixes. The adaptable silvery blue can use these pea family plants as a host.
The vetches in particular, while pretty, are deeply rooted and form dense tangles in grassy areas, choking out some native plants. They’re not something to jump at introducing to one’s yard. I’ve almost face planted tripping over them. These blue butterflies will use them anyway, here is one of their caterpillars on purple vetch:
Notice the ant defender who is enjoying the secretions the caterpillar exudes. And how the usually more green/brown caterpillar has taken on some of the purplish vetch colouring.
The caterpillar will overwinter here in its chrysalis and emerge as a butterfly during the warmer months.
Ontario’s only native lupine is lupinus perennis, the sundial lupine (pictured on left). It’s a wonderful idea to plant this lupine, which is a species at risk in Ontario. Some of the butterflies that use it as a host plant are also at risk. I got my lupine plants from ONPlants.ca, but they’re also usually available at Northernwildflowers.ca and Wildflowerfarm.com to name a few. Pick a mostly sunny spot with moist, sandy, well-drained soil, loosened up for planting. If you sow the seed, inoculate your seeds first (“inoculum” is something you can purchase for legume seeds).
Canadian milkvetch (astragalus canadensis) is another native plant that can host blues and may be purchasable from native plant nurseries. There are also more obscure host plants like native locoweeds (ex. boreal locoweed, oxytropis borealis.)
Adult silvery blues feed on a wide variety of flower nectar, so a pollinator garden packed with a variety of native flowers will meet their needs.
Next month we’re going orange and black with crescent butterflies. In the meantime, Happy Holidays, folks!