Monday’s Massive Migration

For some more info on the butterfly migration see Antonia’s blog plost from May 4, 2012.

They were everywhere across southern Ontario yesterday; even in downtown Toronto. I saw a few in Philosopher’s Walk and across the Bloor St. viaduct. The Red Admirals (Vanessa atalanta) have arrived! One of our more common migrant butterflies, they were spotted in the thousands from Ottawa to Point Pelee and Muskoka. The strong winds blew them everywhere, but the determined little migrants held their ground. A few early individuals had been recorded from late March and in the last couple of weeks but this was a huge wave of them. Glenn Richardson, veteran butterfly watcher and president of the Toronto Entomologists’ Association, reports that this is the largest migration of Red Admirals that he’s ever seen! It is certainly the earliest he has recorded them laying eggs.

Red Admiral (Vanessa atalanta), A Guidotti photo.

Red Admiral caterpillars feed on nettles (see, they are good for something!).  At this time of year, the adults will nectar on any flower they can find such as fruit tree blossoms, dandelions and coltsfoot flowers. They are already busy laying eggs on the nettle; these will hatch and mature for a ‘born in Ontario’ generation of adults later this spring. In Ontario, there may be two or three generations per year. A few Red Admirals have been reported to overwinter in Ontario but the majority of the ones born in August and later migrate south.  Unlike Monarch butterflies, there is no single overwintering location known. Every spring, a new population of Red Admirals migrates from the US.

Red Admiral caterpillar. Copyright Glenn Richardson

Many Question Marks (Polygonia interrogationis, another species of butterfly) arrived in the migratory front and the mild weather enticed some Cabbage Whites (Pieris rapae) and a few other species to fly as well.

Keep your eyes peeled for the return of the Monarchs which is expected in May sometime!

 [Thanks to Glenn Richardson, Don Davies and Peter Hall for their reports.]