In the 1950s or 1960s Galaxy (perhaps) printed a series of short stories about extrasolar people invading the Solar System. The first in the series hight “Only an Echo”. Earth humans called the invaders Jackoes, but did not see them. In one of the stories Earthlings on Mars invaded a crashed or left-behind vehicle using a mini helicopter; they could see a mass detector about to set off the bomb which typically destroyed Jacko artefacts before they could be inspected. A fool of a higher-ranking officer tried to repeat the stunt with a larger mini flyer and predictably exploded the left-behind vehicle. A later story has Earthlings use some information garnered by the mini helicopter for some kind of communication. The Jackoes speak not with their mouths but by clicking two mandibles together, and a prisoner learns to speak their language using tapered chopsticks.
Author? Magazine issues? Anthology? Does anyone besides myself remember anything about this?