During debate on what became the Ragwort Control Act recorded in Hansard on 21st March 2003. Shona McIsaac
MP made some bizarre statements on ragwort
that appear to have no factual basis.
"It is vital to the survival of the cinnabar moth. So we begin to discover how the plague started in the late 1980s. In fact, 1988 was a particularly good year for the cinnabar moth. What happened was that the cinnabar moth caterpillar munched far too much ragwort. Although that sounds like a good thing, the following year, there was nothing for the caterpillars to eat, the moths did not lay their eggs and the predator population of cinnabar moth caterpillars plummeted, so we began to see an increase in common ragwort in the late 1980s. We have to look seriously at the effect of biological controls on ragwort to try to re-establish the cinnabar moth, the existence of which is precarious in Britain at the moment. It is simply not reaching sustainable levels, so apart from all the other methods that can be considered to control common ragwort systemic pesticides, digging out the roots and so on the cinnabar moth is crucial to the argument. Some companies are now looking at such biological controls. "
And later
"It appears that in the late 80s, there was a vast increase in the population of cinnabar moth caterpillars. Usually, the caterpillars eat only the flowers, which results in fewer seeds being released to the wind, but at that time, they started to eat the first year rosettes as well and thus destroyed their own food source, because ragwort, being a biennial plant, did not come back immediately.
This statement is completely at odds with the reality of the data on the cinnabar moth. It is a well-known myth that seems to have been used to promote the false idea that ragwort is increasing when a proper scientific survey over the period shows a decrease.
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