Cannibalism May Be Key for These Cockroach Couples

Singapore Headlines News

For certain cockroaches living inside rotten logs in Asia, nothing says “I love you” like some minor cannibalism. Newly mated pairs of one species, Salganea taiwanensis, take turns chewing each other’s wings down to stubs after they move into the homes where they will jointly raise babies. Scientists say this unique behavior may have evolved because of the roaches’ truly monogamous bond. Sign up for The Morning newsletter from the New York Times Haruka Osaki, who published the finding last month in Ethology, first happened upon some wingless roaches in 2014. She had been collecting insects from the woods as a hobby since becoming a biology student at Kyushu University in Japan the previous year. “When I caught the wood-feeding cockroaches in the wild, I noticed that their wings were chewed by something,” Osaki said. When it was time to choose a topic for her doctoral research a couple of years later, Osaki thought of the roaches. She knew from others’ observations that the damage probably didn’t come from predators, but from cockroaches eating each other’s wings. But she didn’t know why. Her adviser, Eiiti Kasuya, encouraged her to dive in. Osaki collects her study subjects, which as adults have dark, glossy bodies about 1 inch long, from the wild. “I walk into the Okinawan forest and search for rotten logs,” she said. “The cockroaches live in tunnels in rotten wood, so I destroy the wood with a hatchet and pick them up.” She packs the roach colonies into containers, then flies with them back to her laboratory in Fukuoka. After some of her young, wild-caught cockroaches matured into adults, Osaki paired them off in the lab, creating 24 couples. Then she recorded their behavior with video cameras for three days. The videos revealed that the roaches ate each other’s wings in stages. One bug would climb on the other’s back and eat, while the other sat motionless. Then they took a break before they resumed, sometimes swapping positions. At times, the cockroach being mun