Laboratory observations on Ornithodoros moubata (Murr.) showed that the number of batches of eggs deposited never exceeded 8. Young females were able to deposit a second or even a third batch without further blood-meals. The number of matings had no influence on fecundity. Females that mated after each blood-meal deposited eggs that had a higher hatch rate than others deposited by females that mated only once, but their length of life was reduced. The preoviposition period was longer among females that mated once compared with those that mated after each meal. It is concluded that females could produce progeny over a very long time without being totally dependent on blood-meals, and that females infected with Borrelia duttoni could produce infected nymphs several months or even years after they themselves became infected. Thus they act as a reservoir of the disease in the absence of sick people.