depends. usually there is only one sac, but there are instances of a second fertile sac being built by the female without another mating. this happens relatively seldom, but there are species that seem to produce a second (never heard about a third) sac more often.
female tarantulas can 'store' the sperm they receive during mating. they decide when it's time to build a sac and than use that sperm to fertilize them. they can build a sac months or even a year or more after being mated, though usually they do so within the first three months after a mating. my a. versicolor female for example took more than 5 months to built a sac.
oka now is the first sac always infertile.???
Well see yesterday i found out i had a mature male i have two others ones a little too small to sex but the other is female( she's my male's size) i'm putting them together this afternoon but i need to get ready.
a couple questions i need answered:
how do you keep the sac from molding??
i have reptle incubators (for hatching them) would that work to keep the sac in???
How can you tell if a male has mated? and how long does it take roughly for tarantulas to mate?
no, the first sac is usually fertile if the mating is successful. it's not very likely to get a second fertile sac without the female being mated once more though. with g. rosea, you usually get only one sac.
you should stay with the ts while they mate and keep the tweezers ready - it is possible that the female tries to eat the male before or after the mating. if you see some good insertions, the mating should be successful. but to be sure you can try again as soon as the male has built another sperm web. a mating can last a while or be over in less than two minutes - it dependa on the individuals involved.
as for the sac: once a sac is made, i would leave it with the female for at least 30 days before pulling and opening it. make sure that during this time the humidity in the tank is at about 75%. after that time, you should have postembryos that you can incubate in your reptile egg incubator. usually the mother keeps the sac from molding, during incubation hygienic conditions and humidity around 80% is the way to go.
for more detailed information, try the tarantula keeper's guide or the search function. you can also look in the breeding report section here.
not necessarily. there is no guarantee that she will try to eat him, maybe she just leaves him alone. but there is a certain risk, even if he has a larger leg span, so stay with them if you want to make sure he escapes.
if you want to mate your injured male, the risk of him not being able to run in time is bigger of course.
i'm not sure if anyone mentioned this but if a female has laid a sac if she molts afrer laying the sac or any other time BEFORE she has a second sac then the sperm that was stored is actually gone and is void and she won't be able to reproduce unless she mates again to store the sperm again.