Sexing Tarantulas is a very tricky business. Even experts have a hard time sexing a tarantula. A male tarantula could easily be taken for a female if it gets too big.
The best and accurate way to sex your tarantula is to wait until they are fully mature. Females can be identified by looking into their molts for their ovaries. Female specimens will have a skin-like flap in their sexual opening also called the epigastric furrow, just between the upper booklungs, this is called spermathecae. Females will store a male’s sperm in the spermathecae. Female Tarantulas are bulkier and have larger abdomens compared to the males.
Male tarantulas have smaller bodies and the tips of their pedipalps (short leg-like appendages located next to the fangs) will look like boxing gloves. Also males of this specie will develop tibial hooks or spurs on their 1st legs when they reach maturity (tibial hooks are not present in some of the species). These hooks are used mainly to hold the female’s fangs while mating.