There’s nothing quite like sitting outside on a summer day. The sun feels warm on your face. The birds are happily chirping in the distance. And if you’re lucky, the neighbor just mowed the lawn, so the smell of cut grass is fresh and strong. Have you ever wondered why the grass has that wonderful smell after being cut? Today, we answer this question with help from ScienceDaily. 

Similar to the way an animal might growl when threatened by a predator, plants also communicate – through scent – when attacked. 

“Whether by blade of a mower or jaws of a predatory insect – by producing defensive proteins and secondary metabolites either to repel the pest or make itself less appetizing,’” Dr. Michael Kolomiets, Texas A&M AgriLife Research plant pathologist in College Station, says to ScienceDaily. 

Dr. Kolomiets also found that the green leaf volatiles, which create that fresh-cut grass smell, send a distress signal to parasitic wasps. When a caterpillar takes a bite of a plant’s leaf, the wasps fly to the munched-on plant and lay eggs in the caterpillar’s body to kill it. 

“‘We have proven that when you delete these volatiles, parasitic wasps are no longer attracted to that plant, even when an insect chews on the leaf,'” Dr. Kolomiets says in ScienceDaily. “‘So this volatile is required to attract parasitoids. We have provided genetic evidence that green leafy volatiles have this dual function—in the plant they activate production of insecticidal compounds, but also they have indirect defense capability because they send an SOS-type signal that results in attraction of parasitic wasps.”

So, while we might enjoy that fresh-cut grass scent so much that we make candles to replicate it, it has insects flying far, far away.