Milkweed butterflies have been feeding on their own species' live young, caterpillars as sighted by researchers who have suggested they are doing so, in order to increase their mating pheromone supplies.
A Phys.org report mention about Charles Darwin and Alfred Wallace who, it specified, "are only right most of the time." They claimed that the behavior of a butterfly towards their own subfamily members known as Danainae is among one of the most recent discoveries that bring out the question in the evolutionary theory of insects.
This is the first time scientists have found that milkweed butterflies are harassing, subduing, and afterward, feeding on caterpillars that are either alive, dying, or dead. These are those that belong to other milkweed butterflies, the young of their own family.
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Caterpillars Feeding on Toxic Plants
Caterpillars are butterflies and moths' larval phase. They feed on plants, repossessing chemicals for self-protection. The Leafy Place website describes them as coming in various shapes, types, colors, and sizes.
The chemicals caterpillars are sequestering are poisonous and unpleasant to predators like birds. More so, they are later manifested in the bright, warning colors of butterflies.
Additionally, as indicated in this report, these chemicals are helping male butterflies as well, in their production of mating pheromones, which work as "wedding gifts" to their female counterparts during courtship.
To build upon this inherent toxicity, male butterflies are supplementing their diet by searching for additional chemical sources.
More often than not, these sources of chemicals are obtained through plant sources, although in the forests of Indonesia's North Sulawesi, a similar Mirage News report said, it seems that "they have developed a taste for caterpillars," all their searches for the increase of their supplies of this so-called "love drug," suggested the researchers.
First-Time Observation of the Feeding Behavior
Commenting on the result of their study, published in Ecology, University of Sydney School of Life and Environmental Sciences' Yi Kai (Kai) Tea, lead author and PhD candidate, this is the first time such a feeding behavior has been reported.
It does not fit neatly in the customary modes of mutualism, predation or parasitism, explained the lead author, and thus fosters a new challenge to evolutionary theory. The study authors coined the behavior 'kleptopharmacophagy,' chemical theft for food.
The butterflies, to supplement the chemical supplies they obtain as caterpillar juveniles, engage in a behavior called leaf-scratching.
Tea explained, the butterflies are damaging the chemical-containing plants using their sharp tarsal claws, release plant juices and drink them with their long, curly tongues.
Bats of 'Soaked Leaves'
Scratching at these live young, nonetheless, had never been reported before. Caterpillars, the lead author elaborated, are fundamentally bags of soaked leaves.
These are the same leaves containing these potent chemicals the milkweed butterflies are seeking out. To adult butterflies, on the other hand, they may simply be a substitute chemical source on which to feed.
This unusual behavior was observed by Tea, together with his colleagues in 2019, in the coastal forests of North Sulawesi. Specifically, he found adult male milkweed butterflies that scratched at both leaves and live, and dead caterpillars, and seemingly drinking their juices.
Related information about milkweed butterflies feeding on caterpillars is shown on Wayne Breslyn's YouTube video below:
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