Danainae butterflies – leaf scratching and withered plants

“Many plants contain pyrrolizidine alkaloids as a defense mechanism against insect herbivores. In turn there are many insects that consume the plants and build up the alkaloids in their bodies.

“Danainae butterflies (Tigers and Crows) have long been recognised to be attracted to and ‘feed’ on plants of certain genera, both withered and living LINK.

“Here’s a Common Tiger (Danaus genutia genutia) scratching and sucking at a living Rattleweed (Crotalaria retusa) plant which I recorded during a recent visit to Pulau Ubin (top, image; below, video). Such behaviour of Danaine species has been recorded in Hong Kong as the article reports, but perhaps not yet in Singapore.

“In the video below, I recorded a number of Danainae butterflies gathering at a little patch of False Dill (Artemisia scoparia) at Pasir Ris Park, including a batch that had been cut and which lay withering on the ground. As mentioned in the article, the butterflies were probably applying from their proboscides a fluid capable of dissolving the alkaloids and then re-imbibing them.

“Below is a close-up video of a few of them – Dark Glassy Tigers (Parantica agleoides agleoides), Blue Glassy Tiger (Ideopsis vulgaris) and Spotted Black Crow (Eulopea crameri bremeri) feeding on the False Dill.

“Below is an image of a female Striped Blue Crow busy feeding on the withered False Dill.”

Lena Chow
30th June 2014

3 Responses

  1. Lee Chiu San

    Thanks Lena for explaining why Danianae butterflies are attracted to certain types of plants when these are bruised and even withered. Lepidopterists have long known that bunches of the Indian Heliotrope plant (Heliotropium indicum) can be hung up to attract this specific family of butterflies, but few knew the reason. Heliotropium contains the alkaloids that you mention.

  2. Lena

    Glad you found the post useful, Chiu San.

    Here’s a video of Dark Glassy Tigers having imbibed so much of the alkaloids in Heliotropium indicum that you mention, they are in a state of drunken stupor, and one can literally pat them on the head!

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