Are there any poisonous butterflies? Stuart Blackman looks at how chemicals can help butterflies evade predators
Butterflies are unlikely animals – and probably not your first thought when you think of poisonous animals.
Yet not only are they very beautiful, but as day-flying, colourful insects they should be easy targets for predators.
Yet they seem untroubled by such dangers as they flit between flowers. This confidence stems from the fact that many are armed with toxic – or at least distasteful – chemicals – so yes there are some poisonous butterflies. The bright colours warn predators of the danger.
Many, such as the monarch butterfly, ingest these chemicals through foodplants as caterpillars and store them into adulthood. Not all colourful butterflies are toxic, though.
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The hues can serve other functions, such as finding mates. Some perfectly edible species mimic the colours of poisonous butterflies to deter predators without incurring the cost of producing a chemical arsenal.
The colours of African swallowtails, for example, vary with geographical area in order to mimic the local toxic species. From a predator’s point of view, it all adds up to give the general impression that any colourful day-flying insect is best avoided.
Butterflies’ largely nocturnal cousins, the moths, tend to be more muted. However, this trend is bucked spectacularly by many day-flying moths, such as cinnabars, which adopt the butterfly strategy of bright colours backed up by chemical defences.
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