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According to a new study by researchers from Greifswald and Canada, black widows (Latrodectus hesperus) use a unique scent strategy to find their mate. A chemical pheromone slowly decomposes on the female's web, creating an attractant that lasts for weeks, attracting males and governing their courtship.

The study, in the Journal of Chemical Ecology, shows the spider's multi-stage and strategically structured flirting behavior. Unlike many insects, which only release their pheromones at certain times, female widow spiders use their web as a long-term scent transmitter.

The pheromone components on the web have a dual function: on direct contact, they trigger characteristic mating behavior in the males. At the same time, these substances slowly decompose, releasing an aromatic attractant that reminds us humans of "cheesy feet." But male spiders find the scent highly attractive and are attracted from a distance.

First author Dr. Andreas Fischer from the University of Greifswald says, "What I found particularly exciting about the results was that the females adapt the intensity of their scent signals to the time of year. Although they lure males all year round, they are most attractive when most males are looking for a mate." Before Fischer began his research in Greifswald, he worked at Simon Fraser University in Canada.

In the laboratory, the team chemically analyzed the black widow's webs and identified the messenger substances. The researchers also carried out behavioral experiments with male spiders on special test apparatus. Field experiments on a beach showed that the synthetic scent also attracts males in the wild. Monthly measurements from a one-year field study clearly showed that females adapt their attractiveness to the seasons and that day length probably informs them of the upcoming mating season.

"The black widows demonstrate astonishingly sophisticated communication skills: with a complex chemical interplay of flavors and odors, the females significantly increase their chances of successful mating," says biologist Fischer.