wow this thread has proven to be really use full TO ALL who has contributed thanks guys and girls!!!!

ye thanks for the awesome info guys. Really learnt a lot.

I just had a look at the method described ventrally by the link I posted.
I have 3 G pulchripes juvies. Two of them I have confirmed as male via exuvium. The third I was unable to get a sexable exuvium as yet. But the two that is confirmed male, have a dark patch of hair between the book lungs in an arc shape as described and illustrated. The third one has no dark patch. Will have to check the exuvium to confirm, but based on the ventral method, I would say it is female.

I will try and check my 3 B albopilosums as well, when they are sitting against the sides.

Here is the 3 photos. First 2 yellow ones are the males. Third is what I believe to be female. Same instars.
Third one doesn't have the dark patch.

Will confirm female with next molt.
It is a wide picture, so won't insert it here.

Well I for one do not have the need nor time to try and sex every single slings from an egg sack. It's just absurd.

If someone comes to buy slings from me, they can choose which ones they want out of the whole batch.

Quick question: at what 'age' is the sexual organs fully developed?

I agree with you Ceno.
I have 2 (2cm) T gigas slings. It is impossible to see anything ventrally. It barely has ANY hair underneath, almost looks like 1st instar, all smooth, if that makes sense.

Ceratogyrus wrote: One more thing. Dont assume that males grow faster than females. I have bred a few species and keep babies back, and the females have outgrown the males easily a few times.

To add to this- You get bigger and smaller individuals (this can be seen from 1st instar to adult)
aswell as stronger and weeker, therefore different growth rates regardless of gender!
But yes- if i had to put my head:whistle: on a block id always go the smaller ones
from the same sack (from +- 6th instar) to be female! - also depending on sp!

Ive never tried to do the whole sex a sling thing! its silly to say the least!