Olfactory crypsis and visual attraction in a crab spider

There may be an intense interaction or even an arms race between the crypsis skills of sedentary predators and the detection abilities of prey. We explored the issue using a common crab spider and housefly as the predator and prey, respectively. The results showed that novice houseflies did not, but experienced individuals recognized and avoided spider odor. However, spiders responded such detection excellently by utilizing scent of flower substrates to achieve olfactory crypsis. Houseflies could distinguish between the color of spider body against flower, but they preferred rather than avoided the flowers occupied by female spider. This phenomenon may because that the yellow pattern of female spider abdomen act as attractant on white flower petal. Overall, the data provide evidence for the olfactory crypsis of spider, and propose a new potential yellow signaling mechanism for spiders to attract insects.