This is a short post, quick and right to the point - how to tell if your millipede is a boy or girl.
The animals in the picture above are great examples of a male and female Narceus americanus side by side.
You want to pay attention to the seventh body segment from the head. This is where the male millipede keeps his gonads. In this species there is typically two pairs of legs per segment. In males on the 7th segment is missing one pair of legs, but we're not looking for that tiny gap since that's too easy to miss. Instead, the spot where the genitals being housed creates a bit of a bump as is seen in the picture below.
Below is the earlier picture of the Narceus pair and the same swollen segment on the male has been circled again.
As you can see the female next to this male is smooth and the body segments increase evenly in size with no bulge. Another picture right below shows the same lack of bump in a female specimen.
Sexing your millipede is as simple as looking for that bulge close to the head. This is mostly easily seen once the pedes are a couple inches in length. Below that size sexing can be attempted but accuracy is much lower.
Hopefully this short piece has shown you how to determine the sex of your millipedes. If people have any requests as to what blog posts or topics they'd like to see for the future I'm always happy to hear them - leave a comment and I'll be sure to reply asap.
Thanks for reading!