MANITOULIN—2024 was a poor year for monarch butterflies across southern Ontario and the islands of the Great Lakes as it appeared that the northern generation, or offspring of the butterflies that overwintered in Mexico, failed to make it this far north.

Few adults and caterpillars were seen on Manitoulin Island last summer meaning that, for the first time in years, our Island did not contribute to the population that flies south in the fall to overwinter on mountain tops in central Mexico.

Fortunately, 2025 seems to be off to a good start. My wife Marilyn and I have been visiting the boardwalk at Providence Bay on south central Manitoulin weekly since the beginning of May and on Wednesday June 25, we observed at least 10 different adults over a period of about an hour in the mid-afternoon.

These were not the same individuals counted more than once, as they cruised back and forth over the healthy patch of milkweed found on both sides of the boardwalk, since some were freshly emerged adults with brightly coloured wings while others had faded wings which is a sign of ageing. There were both males and females.

The bizarre premating flight behaviour of one male and a female monarch was observed ending with their mating and resting on one of the milkweed plants.

It never ceases to amaze that each of these butterflies had flown across Lake Huron from Michigan likely a day or two before. Some may even have arrived from Michigan that same day if there were strong winds at the altitude they were flying.

One faded male was observed feeding on the flowerhead of a pitcher’s thistle which is common on the Providence Bay sand dunes, but one of Ontario’s most threatened plant species.

It was a noteworthy experience to see on our island one of North America’s most iconic, but threatened species of butterfly, feeding on nectar in the flowerhead of a such a rare plant.

Hopefully the females arriving over the past few days will successfully lay eggs and visitors to the boardwalk will soon see caterpillars feeding on the leaves of the milkweed.

It is important that visitors to Providence Bay restrict their walking to the boardwalk and shoreline where milkweed is not growing.

Trampling milkweed will result in the death of monarch caterpillars. Even brushing against a milkweed plant can result in caterpillars being knocked off the plant to their demise.

by Joe D. Shorthouse