Some "Chrysopa" show evasive behavior when they hear a bat's ultrasound calls: when in flight, they close their wings (making their echolocational signature smaller) and drop down to the ground.
When they hear bat echolocation sounds, they close their wings and drop down.
When they hear bat echolocation sounds, they close their wings and drop down.
Rewrite this with simpler wording: Some "Chrysopa" show evasive behavior when they hear a bat's ultrasound calls: when in flight, they close their wings (making their echolocational signature smaller) and drop down to the ground. Output: