Spiders reproduce sexually and fertilization is internal but indirect. In other words, the sperm is not inserted into the female's body by the male's genitals but by an intermediate stage. Unlike many land-living arthropods, male spiders do not produce ready-made spermatophores (packages of sperm). Instead, they spin small sperm webs on to which they ejaculate and then transfer the sperm to structures on the tips of their pedipalps. When a male detects signs of a female nearby he checks whether she is of the same species and whether she is ready to mate; for example in species that produce webs or 'safety ropes', the male can identify the species and sex of these objects by smell.