the spider away. This behaviour is known as ballooning or kiting. Eventually, the silken thread will adhere to an object where the young spider will establish its own web. They sometimes work cooperatively, climbing, releasing silk and being carried off in clusters. Juvenile spiders build webs, sometimes with other spiders. Reproduction Before a juvenile male leaves its mother's web, it builds a small sperm web on which it deposits its sperm from its gonads and then collects it back into each of its two palps (copulatory organs), because the gonads and palps are not internally connected. After it moults into its last instar, it sets off wandering to seek a female. The male spider does not eat during this period. How males find females is unclear, and it is possible they may balloon like juveniles. A Western Australian field study found that most males took 6 to 8 weeks to travel around with occasional journeys of over , but that only around 11–13% successfully found a mate. They are attracted by pheromones, which are secreted by unmated sexually mature female redback spiders onto their webs and include a serine derivative (N-3-methylbutyryl-O-(S)-2-methylbutyryl-L-serine). This is thought to be the sole method by which males assess a female's reproductive status, and their courtship dismantles much of the pheremone-marked web. During mating, the male redback attempts to copulate by inserting one of its palps into the one of the female's two spermathecae, each of which has its own insemination orifice. It then tries and often succeeds in inserting the other palp into the female's second orifice. The redback spider is one of only two animals known where the male has been found to actively assist the female in sexual cannibalism. In the process of mating, the much smaller male somersaults to place his abdomen over the female's mouthparts. In about two of three cases, the female fully consumes the male while mating continues. Males which are not eaten die of their injuries soon after mating. Sacrifice during mating is thought to confer two advantages to the species. The first is the eating process allows for a longer period of copulation and thus fertilisation of more eggs. The second is females which have eaten a male are more likely to reject subsequent males. Although this prohibits future mating for the males, this is not a serious disadvantage, because the spiders are sufficiently sparse that less