It isn't always easy to tell sexes apart unless you can carefully examine the tarantula using a powerful hand lens. Immature males look much the same as females, while mature specimens of either sex are broadly similar. Generally, the wild-caught tarantulas you will see in pet shops are males because these are so much easier to catch in the wild when they are looking for a mate.

If you are about to purchase your first tarantula, it is unlikely that you will be thinking about breeding in the immediate future. Actually, it is best to gain some practical experience with these animals before you embark on what is a much more involved aspect of the hobby.

The actual act of copulation in spiders is generally quite rapid, this being a desirable need in a species where the female just might eat her mate given half the chance! An average time would be no longer than 30 seconds, though much longer pairings have been observed. Assuming the mating was successful, the female will develop the eggs over a period of five to ten weeks (depending on the species), at which time she will spin a silken web on which the tiny eggs will be laid. In numbers, there can be anything from 50-700 eggs, again depending on the species. Where a large number are laid you can assume that in the wild the mortality rate will be very high, arising from a mixture of infertility, predating, diseased eggs, and cannibalism.

Under captive conditions a much larger number of the offspring can be raised to maturity if husbandry techniques are adequate. This can prove a mixed blessing. Once the eggs are laid the female will carefully wrap these up in silk so that a ball is created. In this the eggs will be incubated for one to four months. During this period the female will rarely stray far from her offspring.

Once the eggs hatch the little spiderlings will quickly scuttle off to seek shelter. If they hang around too long their mother will commence dining upon them! While the spiderlings are still in their silken cocoon they will hatch and experience their first molt. Once they leave the silk ball they will molt again about a week later and repeat the process as they grow. For this part, the male tarantula on maturing will spin a special web on which he deposits his sperm. He will then alight on the web and, using his pedipalps, will draw the sperm into the special mating structures on the tarsal portion of the pedipalps. The tip of this special structure is called the embolus, and it is this that the male inserts into one of the genital openings of the female.

If you decide to mate your tarantula always introduce the male into the female's terrarium, never the other way around as is normal with most pet mammal species.
You should always have a stiff piece of card or plastic available in case you need to separate the two tarantulas rather quickly. The courtship ritual within tarantulas varies from species to species, but in almost all instances the male goes about the task very cautiously.
He may pound the floor with his legs, as well as vibrate his body up and down.

If the female is receptive to his overtures she will respond in a like manner, at which time he will advance toward her.at this point she will rear up and expose her fangs. His reaction is to rush in and use his tibial spurs to lock her fangs in the open position. Having neutralized her danger for the moment, he now proceeds to inseminate her with his sperm. This accomplished, he will release one of her fangs and pacify her by stroking her abdomen with his free front leg.
Finally, the other fang is released and he will make a hasty retreat. Not all mating go this smoothly. If the male is sluggish locking his spurs onto her fangs, she may bite him, and then proceed to dine on him. Once mating has been effected you can attempt a repeat mating a few days later. It is generally held that if the female rejects such a second mating it is a sure sign she was fertilized on the first occasion, but this may not always be the case

Once the eggs have hatched through a small aperture that appears in the egg sack the female should be removed to a new home so the youngsters can grow in safety. The baby spiders can be supplied with a pile of moss, and in this and the substrate they will live for a few weeks with no problems. Of course, the larger and stronger ones will eat the weaklings, but this natures way and there is little we can do about it at this stage. Some fruit flies can be placed in the terrarium on a regular basis to provide food for the growing spiders. After a few weeks it will be time to separate the youngsters, otherwise the death rate will start to rise rather sharply. This is when the hard work really begins, because you may still have 100 or more babies (maybe up to 400!) Each now needing their own home! A stock of small jars with gauze covered lids will be fine, but any sealed container you can obtain in quantity will be satisfactory. This should be half filled with potting soil and little moss or cotton wool that will hold the needed moisture. The babies will need to be fed at least twice a week and with a couple of hundred or more youngsters this becomes a major chore. Microcrickets (pinheads) can also be part of the diet as the little spiders get larger with each molt.