Mating occurs as soon as adulthood is reached. A prior period of heavy feeding, particularly in males, has been seen, but is not thought to be essential. Males search for adult females, but may wait near, or sometimes on, female deutonymphs, suggesting the presence of a sex pheromone. The two sexes make contact face to face, with palps and front legs touching. The male turns over and crawls under the female so that their ventral surfaces are opposite (this takes about a minute). Insemination involves the male inserting a packet of sperm (spermatophore) into the female via a sperm induction pore between the basal segment (coxa) of her third and fourth pairs of legs. The male uses one of his chelicerae (a mouthpart structure also used for piercing and tearing prey) to manoeuvre the spermatophore. Copulation takes a few minutes to several hours. Egg-laying occurs when mating lasts for at least 30 minutes and increases with duration (an average total of 2.70 eggs laid at 30 minutes duration and 66.25 at 131). (Laing, 1968; Amano and Chant, 1979; Sabelis, 1985a, b; Schulten, 1985)
Pseudo-arrhenotoky has been demonstrated (haploid males arise from fertilized eggs, the paternal chromosomes are eliminated during embryonic development). (Helle et al., 1978; Toyoshima and Amano, 1999)