Milbert's Tortoiseshell | Butterfly of the Month

Milbert’s Tortoiseshell Butterfly

Aglais milberti

Milbert's Tortoiseshell Butterfly

"Milbert’s Tortoiseshells are very colorful butterflies, at least when you get to view the dorsal side of their wings as they are flying around or perched with wings spread. They have dark narrow borders on both the forewings and hindwings with blue spots within this border on the hindwings. Interior to this narrow outer border is a wide band of very striking bright yellow-orange. The wing color next to the body is a dark brown with patches of orange on the forewings. With their wings spread, they range in size from about 1.3 inches to 2.4 inches. Adults live for about 10 days. There can be up to 3 broods in a season.

Milbert’s Tortoiseshells are similar to the Mourning Cloak in two ways: they overwinter as adults & when a Milbert’s Tortoiseshell rests with its wings closed they appear to be a previous year’s dried leaf or vegetation and are difficult to see."

"Nettles, often called 'Stinging Nettles,' are the larval host plant for Milbert’s Tortoiseshell butterflies. Eggs are laid in clusters, and the caterpillars will be clustered together in a web on the host plant. The adults’ nectaring plants include thistle, aster, and other flowering varieties.

Watch for Milbert Tortoiseshells in riparian areas where nettles occur.

A tip for butterfly enthusiasts is to look for butterflies in wet or muddy areas along streams or after a rain where they are getting salts by 'mud puddling' or, as Caitlin LaBar calls it, a 'Puddle Party.' There can be a multitude of species and individuals at these locations."

~ Dale Swedberg | Local Naturalist & Retired Sinlahekin Wildlife Area Manager

To learn more about the Milbert's Tortoiseshell, 

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