Subscribe now

Earth

Butterflies use penis to gauge sex competition

By Devin Powell

7 January 2009

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

Male monarch butterflies conduct an all-out sperm war based on a crude measure of how much sperm is stored inside a female from a previous mating

(Image: Stock.xchng)

BUTTERFLY sex is not as elegant an affair as you might think. It seems that male monarch butterflies conduct an all-out sperm war based on a crude measure of how much sperm is stored inside a female from a previous mating.

During sex the males physically restrain the females for an entire day while injecting them with a fluid which contains fertile sperm as well as seemingly functionless cells without nuclei.

Michelle…

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox. We'll also keep you up to date with New Scientist events and special offers.

Sign up

To continue reading, subscribe today with our introductory offers

Piano Exit Overlay Banner Mobile Piano Exit Overlay Banner Desktop