Interstellar Patrol II: The Federation of Humanity

"Vaughan Roberts and his two companions had been trapped on a crime-ridden, chaotic planet until they bamboozled the population with a gigantic hoax - which brought them to the attention of the Interstellar Patrol, who were looking for a few good con men, capable of ingenious improvisation and adept at playing dirty tricks on the bad guys. The new recruits acquitted themselves admirably, so they naturally were given more tough nuts to crack, including: flummoxing an alien empire which has taken a number of human prisoners to gather information prior to an invasion; stopping a plan by not-so-good Samaritans who are pretending to cure a planetary plague - which they introduced to the planet - with a "miracle" drug which creates an addiction to the same drug; and making sure that the rightful heir to a planet's throne escapes from captivity and overthrows the usurper. This time there's a complication: Roberts may be falling for the heir's beautiful sister." And much more, including such lethal alien wildlife as banjo birds with rapier-like beaks, alien caterpillars with flaming dragonlike exhalations, and a cast of thousands of biting, stinging, bloodsucking insects from a host of colony worlds who think humans are the tastiest things they've ever come across.