This Moth’s Love Song Has a Dual Meaning

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When love is in the air for certain moth species, the female secretes a pheromone to signal that she’s ready to make little moths. An interested male will approach and “sing” her a courtship song composed of a series of ultrasonic pulses.

Some types of moth use a “true” song that woos the female into giving the male access to her genitalia. Some other species, meanwhile, lie to get sex. They produce a deceptive song that mimics the echolocation calls of a hunting bat. The female, thinking there’s a predator around, freezes, which allows the male to mate with her even if she’s not interested in him.

Now, scientists in Japan have found a moth that combines the two types, and makes a love song and a lie rolled into one. The yellow peach moth’s courtship song is a made up of a few short pulses followed by a longer one. The long pulse, the researchers found, is attractive to females and hearing it causes them to get into their mating position, like a “true” courtship song. The short pulses are similar to the deceptive songs, and sound, to a moth, like the hunting calls of bats. 

The peach moth isn’t trying to frighten his potential mate like the other liars, though. His deception is aimed at his competition. The researchers found that the short pulses didn’t really affect the female moths. When they heard it, they didn’t move into a mating position, and didn’t freeze or change their behavior in other ways, either. When other males flitting about heard the short pulses, however, they changed their flight patterns and stopped following the trail of the females’ pheromones—the same way they did when they heard a recording of a hunting bat.

The peach moth’s courtship song kills two birds with one stone. The short, bat-like pulses scare off other males so that the first one who reaches a female and starts singing doesn’t have to deal with any competitors. With the rival suitors scrambling for safety instead of heading towards the female, the crooning moth has her to himself, and the long pulse that ends his song put her in the mood for love.