You don't actually, you can take a guess and say to yourself it is going to molt out into a male in the next molt or so but that is guessing.
You could also go on size, but that does not mean anything really, males differ from species to species.

For example, take Psalmopoes species, males normally mature after 12cm or 1 year.
If I remember correctly, a member had a Mature Male mature in 6 or 8 months some where around there and the male was small.

Ok Cool... Now another question... sorry for all these stupid questions but it’s the best way to learn...

Can you determine sex by just looking at a spider from the outside... I know certain males look different to females but I’m talking about juvies – sub adults and by looking on the outside of the spermatheca???

uzi

No stupid questions on here. noob :silly: :drunk:

The only real tarantulas you can sex like that and be accurate is Poecilotheria (pokies) that you sex from the pattern on there carapace and abdomen. (folio pattern)

Other spiders you are taking guesses.
This is called ventral sexing, it gives you a 50/50 chance.

If you know what to look for, you can sex your spiders like that and get it right.
I dabbled in ventral sexing when I started out to try something new with sexing of tarantulas but the most accurate way is to sex the molt.

HAHA yes it must be a 50/50 chance I rely don’t want to have it be an in-between spidy...

I have a P regalis and I would love to know two things...

I bought it from a pet shop and they labelled it as a P regalis but I’ve learnt that they have a white band over the bottom and I don’t see one on mine... Dose it come over time or is it just there?

And is it male or female?

If you can take a picture of the top of the spider, carapace (head) and abdomen (bum) for the sexing.

Like this.

Thanx for asking all these questions Vincent. I've never thought to ask but all this information has been very helpful.

Thanx all.