Nature Scrapbook: The northern spring azure butterfly

A spring azure butterfly on a purple blossom By johannviloria/Shutterstock

Flitting, dodging, never seeming to land, northern spring azures are ethereal specks of splendour, appearing miraculously on sunny, warm spring days. The pale blue butterflies herald the unfolding of the season’s ephemeral blossoms—to which they’re intrinsically tied—along forest trails and watersides throughout Canada to the tree line.

Beneath sun-warmed leaf litter, azures emerge from plump, brown or yellowish chrysalids for their maiden flights, unlike the smattering of other early spring butterflies, which overwinter as adults. Males patrol almost constantly for mates, especially mid-afternoon to dusk. They seem to disappear when occasionally landing to bask, the grey-brown undersides of their closed wings blending with ground colours. Living for only a few days to a couple of weeks, they sip a little flower nectar, but tank up on minerals from mud puddles or even animal droppings.

Female azures, distinguished by their black-bordered forewings, generally mate within hours of emerging. The following day, they lay light-green eggs, spaced individually on flower buds of wild cherry, blueberry, dogwoods, and other shrubs with white spring blossoms. They perish soon afterwards.

Their tiny, squat caterpillars, which can be green to whitish, pink, or brown, hatch within several days, and munch buds, flowers, and developing fruits for two to three weeks before they pupate. As they grow, they secrete a greenish honeydew solution, favoured by sweet-toothed ants. In exchange for the sugary drink, the ants protect the developing pupas from spiders, wasps, and other assailants.

While most northern spring azures stay cooped up in chrysalids for 10 or 11 months of the year, some in southeastern Canada pupate within only a few weeks and fly in summer. In southern Ontario and the prairies, a nearly identical but apparently separate species, the summer azure, also takes wing around the same time.

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