Harvester - Feniseca tarquinius; a butterfly with an interesting approach to life
A recent outing near Molson netted a enjoyable group of butterfly observations including a cooperative group of Harvester butterflies.
Checking my copy of The Butterflies of Manitoba, I found these notes, including this to me startling assertion....
The Harvester is the sole North American representative of a tropical Old World group of carnivourous gossamer winged butterflies.
It turns out that the larvae of this butterfly eat aphids - the Woolly Alder Aphid to be specific. It might be possible that other similar species which also form woolly wax covered colonies may also do.
The butterfly overwinters as a pupa. Adults emerge in the spring in mid May. Eggs are laid adjacent to aphid colonies. Greenish-brown larvae emerge from the eggs and enter the crowd of aphids. The white waxy threads of the aphids also stick to the prominent tufts on the larvae's body segments, helping them to blend in. Only 10-12 days later, the larvae is mature and pupates. In Manitoba, at least two generations are known to occur in a single season.
The population of Harvesters in Manitoba is probably limited by the availability of its prey species. The book describes it as "quite local, seldom abundant and populations fluctuate from year to year"
Woolly Alder Aphids also have a complex life. They start out the season on their primary host variously reported as Sugar maple or Silver maple. The colony formed there creates a generation that move to their secondary host Alders. These are the obvious white colonies on branches that persist through the summer. In autumn a sexual generation is produced that then returns to the primary host.
This story is somewhat problematic in a Manitoba setting as neither of those maple species occur here. It could be that the Manitoba populations are simply skipping the sexual generations and the primary host and only overwintering under fallen leaves or in loose earth beneath alder trees. All reproduction may then be parthogenetic.
it will be interesting to see what we observe.
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