April 1, 2009
How to Sex a Boa
I see this question in forums all the time. How do you find the sex of a boa?There are three ways to determine the sex of a boa constrictor.
- Palpating (or speed bump method)
Probing is basically taking a metal probe and inserting it into the cloaca, pointing it back towards the tip of the tail and insert it towards the left or right side. Males will probe 9-11 caudal scales deep (inverted hemipene) while females will probe 3-4 caudal scales deep. When you probe 9-11 caudals deep, you are obviously probing down into the inverted hemipene. Probing takes a little bit of experience and should only be attempted after you get training from someone with experience. Probes can be purchased at herp shows, some online herp stores, and if you have a good pet store you may find a set there. It’s important to use the correct size probe for the boa. If too small a probe is used on a large snake the hemipine can be perforated or a female can be perforated and get an infection. If it’s too large you may bruise the snake and a male may “probe” as a female because it won’t fit down the hemipene.
Popping a boa is done by putting your thumb below the cloaca on the “tail” pointing towards the head of the boa. Put your forefinger underneath the boa and roll the tip of your thumb toward the cloaca. If it’s a male the hemipenes should pop out. If it’s a female they will not push out. Popping a boa can only be done safely when the boa is very small. As a boa matures the muscles that hold the hemipene in, get stronger and can be damaged if forced out. This method may be the biggest reason some people end up with the wrong gender of boa. If enough pressure is not used a male can sex as a female. If too much pressure is used you can damage the boa.
3. Palpating (speed bump method)
This is the second best method of sexing in my opinion. Probing is the best and most full proof way of sexing a boa. If you don’t have probes or the experience to use them then the palpation method can work great with a little experience. I have to give the credit for this description and image to Dave Colling of Rainbows-R-Us-Reptiles.com.
“Holding baby in left hand, I place my right thumb along it’s spine starting at the vent down. Then with light pressure, slide the tip of a finger from vent towards tip of tail. When you’ve found a male you will know it. Feels like two little bb’s slipping away under the skin. Remember, if you think you’ve gone far enough – go further. Many people are surprised how far down the hemipenal tips are.”
Here is a great example of what Dave is talking about.