How small is too small...?

How big does the t have to be before it's molt/its body can be used to identify the sex? This is probably in the sexing for dummies thread but I didn't want to sort thru the entire forum to find a relevant piece...

I think that if you had a strong enough microscope, you could probably sex a first instar molt.

How about without a microscope, but with a magnifying glass....

That all depends on the condition of the molt, the size the specific tarantula you're sexing reaches as an adult, how adept you are at sexing vents/molts and how good your eyes are.

Basically speaking, you can sex a tarantula when the spermathecae/epiandrous fusillae are developed enough for you to see them with the naked eye behind a magnifying glass. Not a helpful answer, but that's as good as you're going to get without giving a specific species and size. Remember that some species are dwarves, some develop quite late, some species have male accessory organs that are large enough to fool you... So giving a general answer like "you can sex a tarantula when it's X" across" won't really help.

Thank you hobo, that's a great answer. I'll have to go experiment then