This Mantis Attracts Males With a Y-Shaped, Balloon-Like Pheromone Gland

Female dragon mantises attract mates in the dark by inflating a forked, translucent-green organ that researchers say also wiggles

Stenophylla lobivertex
A female dragon mantis with her forked pheromone gland protruding from her rear abdomen. Christian J. Schwarz

Female praying mantises are famously dangerous sexual partners. They sometimes decapitate the male and eat his body once gametes have been exchanged. But new research adds a strange anatomical wrinkle to the love life of an Amazonian species called the dragon mantis.

Researchers discovered that at night, female dragon mantises engage in a bit of sexual advertising by inflating a previously unknown wiggling, Y-shaped organ that emits pheromones to lure in any nearby males, reports Jake Buehler for Science News.

The dragon mantis (Stenophylla lobivertex) is a rare, leaf-mimicking insect found in the rainforests of Ecuador and Peru that measures about 1.6 inches long, reports Mindy Weisberger for Live Science.

This species’ inflatable sex gland first came to light one night in Peru in October 2017. Frank Glaw, a herpetologist at the Bavarian State Collection of Zoology in Germany, was walking through the rainforest at night when he caught a dragon mantis in the beam of his flashlight.

Glaw saw something unfamiliar protruding from the insect’s back. "When I saw the maggot-like structures peeking out from the back of the praying mantis and then withdrew, I immediately thought of parasites that eat the animal from the inside, because that is not really uncommon in insects," says Glaw in a statement.

The glistening, translucent gland is blue-green in color and measures about 0.2 inches long when fully inflated, according to the paper published in the Journal of Orthoptera Research. The paper also reports that each lobe of the gland "can also be moved in a tentacle-like manner."

According to Science News, observations of captive female dragon mantises finally ruled out a parasitic infection and allowed the researchers to home in on the gland’s true function: wafting sex pheromones to attract males. To inflate this smelly love balloon, the mantis pumps it full of a fluid called hemolymph, which is a bit like blood for invertebrates.

“It is a kind of chemical ‘dating app’ in the jungle,” Glaw tells Science News. He says the dragon mantis’ unique anatomical features “emphasize the importance of pheromones in [the mantises’] reproduction in a vivid manner.”

Per Live Science, other species of female mantises are also known to call in nearby suitors with pheromones released from a less showy gland located in roughly the same part of their exoskeleton as the dragon mantis’ protuberance.

“I can easily see something like that being the precursor of the protrusible gland,” Henrique Rodrigues, an entomologist at the Cleveland Museum of Natural History who was not involved in the paper, tells Science News. Rodrigues adds the protruding glands might help the female dragon mantis increase the organ’s surface area and thus the quantity of sex pheromones drifting on the wind to potential mates.

Glaw tells Science News he now plans to look for similar pheromone glands in two of the dragon mantis’ closest relatives to begin probing whether this unfamiliar adaptation might be more widespread.