Translation of the Chinese phrase: "The presence of houseflies is traced to the existence of a corpse."
We know that house flies are attracted to rotten stuff. Thus, when we spotted a "house fly" in our workplace, it is a warning sign of "rotten" (weak)
internal controls. It must be exterminated immediately. Otherwise it will create a "colony of house flies" to feed on fraudulent gains.
From the above painting, only the bigger and arrogant ones are flying above the newspapers showing off their "triumph over the helpless corpse".