A new study on mayflies of the genus Ecdyonurus illustrates just how multifaceted and surprising reproductive behavior in ...

For the vast majority of species, the easiest way to tell an animal’s biological sex is to check out its junk. Does its sex organ elongate and stick out sometimes? A male, in most cases. Is it more ...

Breakthroughs, discoveries, and DIY tips sent six days a week. Terms of Service and Privacy Policy. Researchers in Denmark have discovered six new species of beetle ...

Females of a cricket-like insect found in New Zealand consume male ejaculate after sex to give them enough energy for the following six months of parenting, when they don’t eat. The size of the ...

Females with penislike genitals and males with vaginalike organs are cases of a new extreme reversal of sex roles researchers have discovered in little-known cave insects. These are the first examples ...

You might not know this, but we’re in the midst of an insect shape-studying renaissance. MicroCT technology—basically a lab version of the CAT scanners found at ...

What purpose does the penis serve? Why is it that members of one species have no penis at all, while those of another have two? Why do they vary so much in shape and size? And where do vaginas, or the ...

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 ...