Insect’s organ can be 15 percent the length of the body, extract sperm from males
Courtesy of K. Yoshizawa
The most dramatic genital-shape reversal known — females with long, insertable organs and males with corresponding pouches — has turned up in bark lice living in Brazilian caves.
A female in each of the four Neotrogla species extends a skinny structure up to 15 percent the length of her body to retrieve sperm from the male’s body, reports entomologist Kazunori Yoshizawa of Hokkaido University in Sapporo, Japan. Depending on the species, a female bark louse can spend up to 70 hours extracting sperm. Males have penislike remnants but can’t deliver sperm with them.
Male sperm packages look as if they could be nutritional bonanzas in dry caves where the insects otherwise rely on bat guano and the occasional carcass, Yoshizawa says. The food value of sperm may change the balance of various evolutionary pressures and end up favoring the evolution of female penises and male vaginas, the