For crickets, parasitic flies can stop...( male singers to mate many more times. ...)

Also, many male crickets never sing, apparently finding mates by simply walking around until they encounter females. That raises the question, why sing in the first place" Brockmann said the answer may have to do with the subtle interplay between the density of flies, the density of crickets and the presence of other predators that prey on walking crickets.

Walkers may do better when mates are abundant and other predators are few, while singers may have better luck when mates are relatively rare and fly populations are low. "It might be quite a dynamic thing," she said. "Some years, theres selection against one, some years theres selection against the other."