sexing spiderlings


Old Timer
Jul 18, 2002
we've probably covered this topic before--quite possibly many times--however, i would still appreciate any ideas thrown out to me one how to sex my 1.5" l. parahybana and 3/4" l. cristata. the l. para is due to moult any day now, and the l. cristata has a dark spot on its abdomen indicating a moult to come.

the only magnification resources i have are a child's microscope (which magnifies up to 100x, however, the light is underneath and you can't see well with the moult covering up the lightsource) and a teeny plastic magnifying glass.

any ideas on practically fool-proof sexing using only these materials?

Vayu Son

Avatar of Anansi
Old Timer
Jul 19, 2002

No fool proof method at that size unless you are able to both

1.manipulate the shriveled abdomen and open it without destroying it

2.locate the epigastric furrow with a pretty good microscope. what your looking for on females is a 'leaflike' extension in the center past the booklungs near the abdomens connection to the thorax. or opisthoma to prosoma, respectively.

visual aid:

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Code Monkey

Old Timer
Jul 22, 2002
At 100X you can see the difference between the epiandrous fusilae and normal hairs on a male anterior of the epigastric furrow (in fact, you can see it at 40X), but the difference is pretty subtle. I was all gung ho about it for a bit, but after looking at a bunch more and watching some of the slings I "sexed" that way grow larger, I'm thinking I need some more practice before I'd ever call it even close to full-proof. My one sure fire female is looking semi masculine, and one of my sure-fire males is looking more like a possible female.

I've got a B. smithi I'm 90+% certain is an immature male, so I'm going to keep doing comparisons with it until I've got it down better. In theory, if you got good at it, you can sex at that size with a high degree of certainty.

For looking at something like a moult, you should be able to see it fine assuming you've spread the abdominal area you're looking for flat with under lighting. I cut the region out and suspended it in a bit of water when I was fooling with it.

Truthfully, though, I suspect it's all a bit too much trouble. By the time it really matters, you can sex them with the naked eye without any problem. It's not like we're arranging marriages for them 10 years in advance :D