responsible-2
Explanation
The Joke
A financial advisor-type figure lectures someone, saying "It's really not responsible to have kids before you have enough savings to do that. You need to get an education, get a good job, and for you to accumulate 20 years' worth of free..." The other person asks "Tell your friends?" The comic then cuts to a newspaper headline: "MOSQUITO POPULATION PLUMMETS," with subheadlines reading "Economists No Longer Most Hated Profession" and a graph showing a declining population curve.
The joke works by connecting two seemingly unrelated ideas. The first panel presents the common real-world advice that people should wait until they are financially stable before having children. The punchline extends this logic to its absurd conclusion: if everyone actually followed this hyper-responsible financial advice, people would delay reproduction so long that the human population would collapse -- and with fewer humans around, the mosquito population (which depends on human blood) would plummet too.
The Humor
The comedy comes from taking perfectly reasonable-sounding financial advice and showing its catastrophic demographic endpoint. The newspaper format in the final panel sells the joke by treating the collapse of human reproduction as just another news story, complete with the darkly funny aside that economists are "no longer most hated profession" -- presumably because everyone finally took their advice and it led to near-extinction. It satirizes both the unrealistic expectations placed on young people before they are "allowed" to reproduce and the tendency of economists to give advice that sounds rational in isolation but would be disastrous if universally applied.