Butterflies feed on live young to steal chemicals for ‘wedding gifts’

by Loren Smith, University of Sydney
September 9, 2021

Charles Darwin and Alfred Wallace are only right most of the time. A butterfly’s behaviour towards members of their own subfamily (Danainae) is among the latest discoveries that raises questions in insect evolutionary theory.

Scientists have discovered that milkweed butterflies harass, subdue, and subsequently feed on live, dead, and dying caterpillars belonging to other milkweed butterflies – that is, their family’s young.

Caterpillars are the larval stage of butterflies and moths.

Caterpillars feed on toxic plants, sequestering chemicals for self-defence. The chemicals are noxious and unpalatable to predators, such as birds, and are later manifested in butterflies’ bright, warning colours.

These chemicals also help male butterflies produce mating pheromones, which function as nuptial ‘gifts’ to females during courtship. To build upon this innate toxicity, male butterflies supplement their diet by seeking out additional sources of chemicals. Most frequently, these are obtained through plant sources, but in the forests of North Sulawesi, Indonesia, it appears that they have developed a taste for caterpillars – all in their quest to increase their supplies of this love drug, the researchers posit.

Keep reading: https://www.sydney.edu.au/news-opinion/news/2021/09/09/butterflies-feed-on-live-young-to-steal-chemicals-for–wedding-g.html

Read the Ecology paper: https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.3532