Kleptopharmacophagy

[3][4] The phenomenon was first noticed in milkweed butterflies that were attacking caterpillars and drinking their internal liquid, proposedly to obtain toxic alkaloids used for defense, as well as for mating purposes.

[2] Milkweed butterflies have also been previously seen feasting on some moribund pyrgormorphid grasshoppers, that are known to contain toxic alkaloids,[2][8][9] as well as obtaining desired chemicals from carcasses of dead insects of different taxa.

[8] Similar behavior was observed with adult butterflies scratching leaves of different plants that possess various toxins in their vegetative organs (so-called leaf-scratching[6]).

Adult male danaine butterflies use their sharp tarsal claws to scratch and damage leaves of plants that contain high levels of pyrrolizidine alkaloids, thereby liberating the juices for consumption.

[2][10] Since kleptopharmacophagy was recorded and described only a few times,[4] it is thought that obtaining such chemicals by feeding on plants with alkaloids is a common and more frequent way of stocking toxins.

A group of danaine butterflies feeding on the caterpillar of Idea blanchardii blanchardii . From left to right: Euploea algea kirbyi , Ideopsis juventa tontoliensis , Danaus ismare ismare .
Kleptopharmacophagy was first observed in milkweed butterflies. Here a male Ideopsis vitrea vitrea is seen scratching and feeding on the caterpillar of Idea blanchardii blanchardii .
Parantica algeoides algeoides feeding on a dead arctiine moth. Arctiine moths are known to be chemically defended by pyrrolizidine alkaloids. In cases where the carcasses of alkaloid containing insects are preferred, the term necropharmacophagy may be more applicable.