Naturalist's Worksite News


2023 Report of Monarch Butterflies - Nova Scotia

The year 2023 had a slow start for Monarchs in Nova Scotia, probably due to the cool weather of the late spring and early summer. Very few Monarch had made it to province before mid-July. We saw the first Monarch in our field at Brooklyn Corner, Kings County on the 14th of July and found the first eggs layed the very next day. More Monarchs arrived over the next 10 days and these added to the breeding activity. The females must have been already fertile since we never saw a single coupling of male and female at all the year.

Because the laying start late, the first eclosure was not until 15th of August, just as the Monarch go into diapause and can not breed to raise a second generation here in Nova Scotia.The last egg was layed on the same day of the first eclosure. More Monarchs appeared in the field after that time as the laying between mid-July and mid-august resulted in caterpillars and chrysalis populations increasing. By late August the numbers of butterflies peaked in the midddle to high twenties.  Our nearly daily counts of the numbers in the field are shown in the graph here.

Graph of 2023 Count of Monarch Butterflies in the FieldThe Monarchs were ready to leave for the south as they came out of the field . We did find eggs and a few caterpillars on Common milkweed in our lawn and protected them until they emerged from their chrysalis. All total we released 71 and tagged 50 of them. But we seldom saw the tagged Monarchs in the field.

This year was quite a contrast from 2022 and other years when the Monarchs arrived in June and a second generation of Monarchs were created by those that eclosed before mid-August. In those cases we saw two peaks in the population of the field, one for the first generation and one for the second. That second generation was always a much larger population, sometimes numbering at 60 or 80 at the peak. (See my reports for 2020, 21, and 22)

I also survey nearby Common milkweed plots and found very little evidence of Monarch presence. Normally in other years I would find eggs and larvae in most plot, but this year I only found some in two plots. I only saw one Monarch butterfly outside our field and many naturalists in Nova Scotia saw none until late in the summer when the migration south was taking place.

Next year the weather may favor the Maritimes with an earlier start to the Monarch season.

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