Mutant insects? Where! Show me!
Lower the Raid can, Kemosabe. Mutant insects (as a potentially society-ending entity) don't currently exist. But that's not to say they can't, and, as sean b so gently pointed out, it's high time we devote a little time to getting your MISP off the ground.
Insects do two basic things: eat and reproduce. They're small, they move in swarms, and they all have ways of attacking humans. Why haven't they consumed the planet by now? Because they're at the bottom of the food chain. Everyone eats bugs - even some plants. Insects are getting gobbled up so fast it's a miracle there are any left. It takes constant breeding just to stay alive.
If you are annoyed by the presence of insects around your home, it's a simple matter to break out the pesticide and clear the area. Bugs can sometimes be annoying, but they're never a real threat.
Mutations being what they are, however, it's impossible to predict the future. Insects would require only minor changes to become incredibly threatening. Let us assume, for instance, that a given insect lost susceptibility to modern insecticides, or doubled its rate of reproduction. Suddenly, the current delicate balance of existence would be upset and insects would take over the world. Let us examine:
Termites consume dead plant material (wood). This means the agricultural threat is not total (trees and vines will be destroyed while grains and legumes survive), but the danger to modern society is still very gret. Wood and wood fiber products (like cardboard and paper) have been of critical importance to infrastructure for millennia. Widespread termite damage would cause buildings to collapse and paper records to be destroyed. The vast majority of the human population would be without shelter. Forests and jungles would vanish and shipping would grind to a halt.
Civilization would face desperate turmoil for several years until metal and plastic building materials became cheap enough to restore basic construction. Refugees would roam aimlessly in search of shelter. The global economy would collapse and then implode.
A few words of advice: fighting termites is about protecting yourself. Build your home with metal framing; use synthetic insulation; coat your drywall with a thick impermeable plastic. As always, be sure to have enough weaponry to deal with swarming refugees who want to live in your termite-proof house. If you work in construction, manufacturing, or transportation, get a new job presto.
Locusts are not directly threatening to humans but they devastate agriculture. Before modern insecticides, locust plagues were capable of causing devastating famines causing tens of thousands of deaths. Entire regions find themselves completely devoid of crops after a locust swarm descends; it often takes years to recover.
A locust apocalypse would consume above 90% of the planet's current plant life. This would have devastating short and long term impacts. Short term: massive food shortages would cause billions of people to starve to death. With survival on the line, countries would be forced into war over the remaining stockpiles, and rationing would give way to corruption and blackmail. The rich and powerful would pay their minions with food and play subfactions against each other; anarchy would reign. The geopolitical structure would devolve into a caricature of dogs squabbling over meat.
Civilization would collapse under the weight of rapid depopulation and the world would be plunged into a post-apocalyptic stone age. Regions safe from locusts (mostly the polar areas) would be invaded by survivors who would fight bitter wars to the death over the space. Civilization would slowly return, only to face the long-term impact of a locust apocalypse: atmospheric imbalances.
Flora and fauna are extremely co-dependent. Here's a basic idea, courtesy of Mountain Empire Community College:
See how that works, boys and girls? CO2 > plants > O2 > animals > CO2 > and so on.
Take plants out of the equation, and you have a broken chain. O2 gets used up and converted to CO2 but it's never converted back. What happens now? Do we all die? Not quite - there are special machines that can decarbonize CO2 and maintain the atmosphere in a small, closed system. But we don't have the technology to keep the whole planet going. Human life will go underground and exist in air-tight cities. With post-anarchic government settling back down in easy-to-control spaces, totalitarianism will see a sudden resurgence. Citizens will be forced to toe the line to get food and oxygen or be exiled to the lifeless surface.
Preparation for a locust apocalypse is simple: first, have a survivor party capable of fighting for food if and when necessary. Second, stockpile food and make sure no one outside your survivor party knows about it. Have enough to keep your party alive for several years with some left over. Use the leftover food to buy power in one of the brutal dictatorships of the post-locust world. Third, move to the Rocky Mountains.
Africanized honey bees (also known as Killer bees) are some of the most potentially dangerous critters on God's green earth. They have everything that makes normal bees dangerous (potent, fast-acting poison, wide hive coverage, excellent communication, super-dynamic body), with the added comfort of a scent "tag" they place on enemies, causing all nearby bees to swarm and sting the target. If you're tagged by a killer bee, you're in very deep doo-doo.
A sting from a single bee is not dangerous to those of us who don't suffer from bee allergies. In fact, it's possible to develop an immunity to bee toxin (ask a bee keeper about the last time he was stung). Some cultures even use dried poison for medicinal uses to stimulate the immune system. But there's no coming back from a bee swarm. Poison effects every part of your body; swelling some things, shutting down others.
Killer bee apocalypse would cause the deaths of billions of animals, from lizards to humans (and yes, in between). Depopulation would be just the beginning. Because bees don't need their victims to survive, they could exist on the surface indefinitely, and without sufficient quantities of herbivores, plant life would rapidly overtake the planet. Humans would be forced into ironclad cities safe from both insects and the ravaging plant sprawl. With every passing year, the bees would become more prolific and life on the surface would be more impossible.
As with many apocalypse plans, you must be able to identify a killer bee invasion before it becomes serious. Get into densely populated areas, where you can stay indoors and where plant life (which is what attracts bees) is more scarce. No matter how safe you feel, never remove your protective mosquito netting. Better safe than sorry.
Life underground won't be easy, but neither will adjusting to the post-anarchic totalitarianisms of closed-city governments. You'll need a plan to adapt to harsh new realities - but that's a topic for another Monday.
Got your own Survival concerns? Comment below with your own life-and-society threatening scenario for a free expert analysis.