Why Some Butterflies Want to be Ants

Some butterfly species seemingly want to be ants, a new study says, infiltrating the insects' homes and mimicking ant sounds so they can hide away in their comfy nests.

Ant nests are well-protected, environmentally stable and resource-rich spaces - in many ways a safe haven for all sorts of tiny creatures. And recognizing how good ants have it, butterflies wanted an in.

For the thousands of species of insects that squat inside ant nests, survival means finding ways to live with the army of ants. Maculinea butterflies, which infiltrate the nests of Myrmica ants and spend most of their lives there as unwanted guests, have learned to warp ant "words" to suit their own twisted tastes.

"Acoustic signals convey quite complex information, not only between worker ants while outside the colony, for example during foraging, but also within the nest and between castes," Francesca Barbero, the lead researcher from the University of Turin, Italy, said in a statement. "We aimed at understanding whether some ant social parasites, such as butterfly larvae, could interfere with their host ant communication system."

Over the years, Barbero's team has recorded and analyzed the sound signals emitted by larvae and pupae of Maculinea parasites and by queens and workers of the Myrmica host ants. These clever nest-crashers know that worker ants obey the reigning queen ant, and so decided to copy her sounds. Queen ants make are distinctive sounds from worker ants inside colonies, and the new work shows that these parasitic butterflies capitalize on that difference.

The researchers found that ants bamboozled by the sounds would even feed butterfly caterpillars more so than their own offspring - a type of privilege normally reserved for the queens of the nest.

Barbero and her colleagues next plan to assess the role of acoustical emissions in other butterfly-ant interactions.

The findings will be presented at the 168th Meeting of the Acoustical Society of America (ASA), to be held Oct. 27-31.