Pollinator of the month: Milbert's Tortoiseshell (Aglais milberti)

Milbert's Tortoiseshell (Aglais milberti) is the only species of tortoiseshell native to North America, while the other three species are native to Europe. The genus name Aglais originates from the Greek word ‘algos’ meaning beautiful. The species name milberti is said to originate from the name of a friend of Jean-Baptiste Godart, the entomologist who discovered the species. The common name ‘tortoiseshells’ comes from the resemblance of the upper wings to the yellow-brownish spotted shell of sea turtles. They are found throughout Canada, Alaska, and the Northern and central United States and are present at all elevations. They commonly inhabit wet areas where nettles are nearby; this includes moist pastures, woodlands, wetlands, and roadsides.

Tortoiseshell lay their eggs in clusters on the underside of stinging nettle (Urtica) leaves; which then hatch into the larval caterpillar form and use the nettle leaves as a food plant that they feed on until they are ready to metamorphosize. Then, they fashion a cocoon made of the nettle leaves and spun webbing around themselves and enter the dormant pupae stage to develop into adult butterflies. In their adult stage tortoiseshells act as pollinators; their preferred flowers include thistles, goldenrods, milkweed, and lilacs.

Tortoiseshell have roughly a 4 - 6 cm wingspan, and wing patterning is the same for both male and female butterflies. Their body is brown and appears hairy. They can be identified by the dorsal (upper) side of the wings (visible when spread) have a wide orange submarginal band that transitions to a pale yellow on the innermost section of the band. There are black marginal borders around the wings that contain small blue crescent shaped markings on the back of the hindwing. The most medial section of the wing is black adorned with two bands of red on the forewing. The ventral (under) side of the wings (visible when closed together) are a dark purplish-brown. The ventral submarginal band is a tan colour. Edges of the wings are scalloped, and the forewing is squared off at the tip.

If you have additional knowledge/information about Milbert's Tortoiseshell, how to identify them, or good resources about the Aglais genus, please feel free to share!

REMINDER
May Community Pollinator Walk (weather dependent)
Saturday May 27, 2023, from 1:00pm at Weaselhead/North Glenmore Park
Meet at the Weasel Head Natural Area Parking lot, off 37 St SW
Register for the walk here

We hope to see you there!

Posted on May 21, 2023 04:48 PM by jdo77