The king of the butterfly world is sadly in decline – and scientists are wracking their brains to find out why.
The monarch, known for its brilliant orange wings and contrasting black and white sections, has seen its numbers drop dramatically since 2000.
The herbicide Roundup was quickly identified as the suspected culprit – but now the boffins aren’t so sure.
Ireland has 32 resident and three common migrant butterfly species.
The monarch is not a common visitor here but can sometimes be seen on the south and south-west coast.
It is usually spotted in September and October but they do not hibernate here as they cannot survive our winters. There are also no natural breeding habitats for monarchs in Ireland.
Science writer Gabriel Popkin said: “American monarchs are famous for their seasonal migration.
“Western monarchs breed west of the Rockies and fly south to overwinter in California.
“Eastern monarchs breed on the Great Plains and Canada and fly south, covering up to 160km a day, to overwinter in Mexico.
“Numbers of monarchs overwintering in Mexico have been in serious decline over the past three decades with a 66% reduction between 1997 and 2007.
“This timeframe coincides with the introduction [in 1996] and large-scale deployment of Roundup, the Monsanto herbicide based on the chemical glyphosate.”
Roundup kills milkweed plants, where female monarchs lay eggs. But scientists also believe a parasite could be infecting the butterflies as they migrate towards Mexico.
It has been a divisive issue and until the source of the problem is uncovered the monarch will remain at risk.
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