Sexing too soon ?

[Matthew Bagley]

My luck seems to be continuing . It seems that nearly every T I get that isn't mature seems to come out male . Excluding my OBT (and not too sure it's mature yet and hasn't been sexed) all my AF's have been bought in mature .

I've started trying to sex every shed i get using my USB microscope and the few I've managed look male . I'm talking about a shed 2-3" LS . I'm getting good images esp when you consider that state most slings leave there old skins in .

Now are they too small ? Is there an age where there's nothing to see or can you sex a female as soon as it's hatched ?

My count of T's sexed excluding my purchased females .

Female
P.murinus (?)

Male (MM)

P.cambridgei
P.irminia
P.pulcher
G.sp.'concepcion'

Male (as sexed)
A.geniculata 3"
E.refescens 2"
Phlogeillus sp.'Goliath' 2 1/2 "
B.ablopilosum 4"

I'm thinking of advertising my services as a male T supplier .

[Craig Moore]

Haha I know how you feel- bought my first T 4 months ago on the basis that it was a female and "she" turned out to be a mature male last month. It's whatever way the cookie crumbles I suppose but pretty annoying considering I paid £55.
Anyway - back to your question, 2-3 inches isn't too small at all to sex a spider. I've know of experienced people being able to confirm sex from a very young age.

[Andrew Ferguson]

The kind ladies and gents of the BTS sexed my very young (approx 2.4" legspan) B.smithi for me.

We'll find out for sure in about 3 years if they were right, but I'm 99.9% sure from all the responses.

http://www.thebts.co.uk/forums/showthread.php?t=3841

[Craig Moore]

I found this to be really fascinating from a previous thread.. http://tarantulas.tropica.ru/en/node/586

Shows the spermathecae of different species when identifying a female tarantula. As you can see in certain species it's quite subtle, very pronounced in others - amazing creatures

[lynn mawdesley]

Mikhail's website is excellent indeed

I know how you feel Matt most of mine have matured into males , but then its less pressure on me for a resulting sac im just the spider sperm supplier haha

[Eleanor]

I've also spent some time in the past attempting to sex spiders when they're very small, and taking photographs along the way to see how reliable it is at different sizes. Luckily this was long enough ago now that the success (or not) has been proved! I always meant to post the results of this up for people to see but never got around to it. Maybe one day.

You can sex them at the size you describe, but there is a size at which they are too small, too - hatchlings really don't show any difference you can see.

Some species are easier than others, too, and there were one or two that I did get wrong when they were very small (B. vagans males have some organs that can look a bit like spermathecae, but particularly so when the spiders are very small, for instance). And some species are slower than others to get spermathecae big enough to look really distinct. Keep looking as they get larger, and you'll get to see how well it works for your species.