One cool but sunny and dry October morning, I saw a large butterfly arrive in my back yard. Of course, I grabbed my camera and stealthily stalked slowly out the side door to shoot around the corner of the house.
How Many Flights of Black Swallowtails Fly Each Season in Southern Ontario?
Some southern Ontario butterflies have several generations between spring and fall. Others only have one generation take wing after each winter.
A Silvery Blue
For example, near where I live, you only see Silvery Blue butterflies on the wing once a year. Once one generation has flown to mate and lay eggs, no more emerge to fly until the following year.
An Eastern Tailed-Blue
However, Eastern Tailed Blues in this neighbourhood have at least two generations. The first flies, mates, lays eggs, and is gone. For weeks, I will not see a single Blue butterfly. Then poof, out bursts another generation and suddenly I’m sharing the path again with patrolling Blues.
According to the ROM Field Guide to Butterflies of Ontario, Black Swallowtails in southern Ontario typically have two generations.
Do Black Swallowtails Over Winter As Adults?
Again, according to the ROM guide, a Black Swallowtail usually over winters as a chrysalis.
That does not bode well for this October visitor to my garden. It’s unlikely that it can find a mate, create eggs, and have the caterpillars from those eggs reach the chrysalis stage before winter sets in.
In the spring, though, I will hope to be proven wrong by seeing one of its offspring!
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