The Mourning Cloak Butterfly – Harbinger of Spring

Some might say that the song of the Cardinal is the first sign of the coming spring in Toronto. But it is difficult to imagine when it’s February and there’s snow on the ground. For me it’s the appearance of the Mourning Cloak butterfly (Nymphalis antiopa) that means spring is here.

The Mourning Cloak overwinters as an adult. It may find a niche under loose bark or roof shingles, a tree cavity or an unheated building to spend the winter. It often emerges from hibernation before the snow has melted  making it one of the first butterflies to take flight in the year. I usually see it beginning in mid March. Surviving for up to 1 year, it is one of the longer lived butterflies. There are two generations per year in Ontario. It is native to North America and Eurasia.

The Mourning Cloak larva (also referred to as a caterpillar) feeds on a large variety of host plants including willows, poplars, elms and hackberries. The larva’s spines are a deterrent to predators. It remains with its siblings for some time and they will vibrate in unison when disturbed . When the larva reaches full size (approximately 5 cm) it will wander off in search of a site to pupate. This larva was found in High Park in mid July.

In mid June, I spotted a Mourning Cloak larva wandering about the wall of a building at my work place near the east Donlands. A few days later I found this pupa (also referred to as a chrysalis in the case of butterflies) on the same building. The pupa is approximately 2.5 cm.

A week later the adult Mourning Cloak had emerged. Here it is waiting for its wings to inflate and dry.

The wingspan of the Mourning Cloak is approximately 7.5 cm although it can reach 10 cm. The dark brown wings with beige trim and blue spots make this butterfly easy to identify. The dark colour allows it to absorb more heat when basking in the sun. This is helpful to early spring butterflies as they need to stay warm to be able to fly. The Mourning Cloak will aestivate (enter a dormant state similar to hibernation) at some point during the summer, later re-emerging to feed and store energy for overwintering. This Mourning Cloak was found at Guild Park in mid September. It was probably obtaining minerals from the wet sand.

Adult Mourning Cloaks feed on tree sap and rotting fruit and only rarely on nectar so they do not contribute very much to pollination. A diet of tree sap allows the Mourning Cloak to appear so early in the year. Here a Mourning Cloak butterfly along with a Comma butterfly (Polygonia comma), another early spring butterfly that overwinters as an adult, are feeding on tree sap at L’Amoreaux Park in early May.

Mourning Cloak refers to the butterfly’s resemblance to a cloak once worn when in mourning. Nymphalis is a derivation of nymph, a female nature spirit in mythology, and also refers to a fountain. Antiope refers to a number of female characters in Greek mythology. Why this binomial name (Nymphalis antiopa) was applied to the Mourning Cloak butterfly is not clear.

References

1) Butterflies of Ontario – ROM Field Guide – ISBN 978-0-88854-497-1

2) Butterflies of Toronto – City of Toronto Biodiversity Series – ISBN 978-1-895739-62-6

3) Animal Diversity Web – http://animaldiversity.org/accounts/Nymphalis_antiopa/

4) Nature North – http://www.naturenorth.com/spring/bug/mcloak/Fmcloak.html

5) Nymphalis antiopa – https://en.wikipedia.org/wiki/Nymphalis_antiopa

6) DesertUSA – http://www.desertusa.com/insects/mourning-cloaks.html