We've always had a weird double standard toward non-humans. We'll build elaborate habitats for hamsters and dress them in tiny costumes, but will poison a rat without a second thought.
In the midst of those arbitrary rules it's easy to lose track of the fact that some of the most hated pests are also the ones that least deserve it. Well, we're here to ask you to reconsider...
The thing about cockroaches isn't just that they're incredibly gross and/or disease-ridden, but that they insist on living right in our kitchen. Most people would rather see a freaking ticking time bomb in their cabinet than a nest of these bastards.
But the reason why roaches survive so well around your boxes of twinkies is that for centuries they were like our tiny, industrious little roommates. Cockroaches specifically adapted to share the nests of larger mammals, getting access to a continuous stream of food scraps, mold, mildew and even the delicious eggs of more dangerous insects such as fleas, bedbugs or lice. In return, us larger vertebrates are supposed to enjoy the free janitorial service and snack on the ones that don't run fast enough.
For most of the animal kingdom, it's still a pretty sweet deal. But a few centuries back, we humans decided we could keep ourselves clean without an army of hungry bugs, and our former custodians became just another form of "filth" to our high and mighty standards.
And just how filthy are the little freeloaders? Well, that depends.
If you happen to live directly over an open sewer or keep decomposing corpses under your floorboards, it's entirely possible that your cockroaches might be tracking the occasional pathogen on their sticky little feet, but their habit of incessant, cat-like grooming tends to rid them of contaminants long before they might scuttle over your ham sandwich.
In fact, testing shows that germs don't even stick to them that easily in the first place, so they're really only as dirty as whatever they're standing on at the time.
So, we know that roaches just aren't very dangerous... but we would still be better off without them, right? Sure, if you don't mind the wafting diseases that'll build up when we lose a major player in the process of decomposition. Cockroaches are also the primary predators of bollworm and armyworm, two of the most destructive pests of cotton, soybean, corn, cabbage and tomato crops in the United States and Africa.
Really, it's just a PR problem at this point. Maybe Pixar just needs to make a movie starring one of these guys.
"I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars."
-Charles Goddamn Darwin
A huge wasp flying into an office full of people has about the same effect as a crazed gunman. "Aaaahhh! Wasp! Here he comes! Ruuuunnn!! Find out what he wants, and give it to him! "
"You want my daughter? You can have my fucking daughter!"
When wasps aren't pumping us full of excruciating venom, they're condemning other insects to some of the slowest, most grotesque deaths in the natural world. A parasite that devours its host from the inside out is known scientifically as a parasitoid, and the vast majority of parasitoids in nature just happen to be wasps. They are even believed to have assimilated a fucking virus to make their sting even nastier.
Cockroaches, caterpillars and even spiders fall victim to their insidiousness, becoming the walking dead; chemically enslaved incubators to ravenous wasp larvae.
Parasitic wasp cocoons attached to a caterpillar. Go ahead, try and count them. From Alex Popovkin on Flickr.
The thing is, this sort of devilry is precisely why the world would be worse off without these little sadists. Predatory arthropods such as spiders, dragonflies and ladybugs all have a hand in maintaining nature's delicate balance, but none are so geared towards grand-scale pest control as parasitoid wasps, who have not only evolved to track down and slaughter specific plant-destroying insects, but the rest of the natural world has evolved to help them.
For example, let's take a look at ordinary, everyday corn. When stalks of this staple crop find themselves infested by caterpillars of the species Spodoptera exigua, the plants release a chemical concoction that attracts the species of wasp designed to fuck up that particular caterpillar. If it's dealing with some other type of caterpillar, like Mythimna separata, corn sends out a modified signal designed just for a different wasp that will kill it.
Yes, fucking corn has evolved a means of saying "please inject brain-eating embryos into the worms that devour my precious tissues. No, not you, these are the other worms. Yeah, send those guys. Thx."
Scientists aren't sure just how many different wasps one plant can keep in its chemical rolodex, but many are believed to have a unique emergency broadcast for every local pest that may munch on its foliage.
And it's not just the vegetable kingdom that benefits; some wasps hang around large mammals to pick off biting horseflies and even the dreaded bot-flies.
Just as your immune system continually adapts to new strains of the common cold, wasps function as an ecosystem's own "antibodies" against all manner of infectious, invasive vermin. It really is one of the fundamental laws of all living things: You must tolerate douchebags if they're keeping out the bigger douchebags.
The most widespread of all mammals that don't walk on two legs or drive cars (at least not yet), rodentia of the Rattus genus are most famous in Western culture as sewer-dwelling, corpse-nibbling cornucopias of contagion who gnaw their way into our homes and use our cereal boxes as toilets.
To be fair, a part of this monstrous reputation is firmly rooted in reality. Besides costing us billions of dollars a year in property damage, rats are one of the most widespread ecological pests in the world, feasting on defenseless native wildlife wherever they've been introduced and even driving other species to the brink of extinction.
On the other hand, the same can be said of a much larger, even more destructive species that happens to be reading this very article as we speak, and while your average person finds rats at least a little creepy, it's probably not because they eat endangered kiwi eggs. Filth, plague and pestilence are what rats are known best for in popular culture, and any extermination company will tell you that rat germs are an immediate, serious and costly threat to you and your entire family.
Oh, but not that costly. They have a very reasonable payment plan. Nothing's too good for your family, you know.
But if rats are really such a biohazard, one must wonder why we don't hear about it more often. If you're living in a city, chances are good you have thousands of the precocious imps breeding right under your feet at this very moment.
The truth is that while you certainly shouldn't pull one out of a storm drain and put it in your mouth, there isn't any scientific basis to assume that rats are exceptionally disease-prone animals. This stereotype primarily stems from the infamous Black Death, an outbreak of bubonic plague speculated to have killed over 75,000,000 people during the mid-1300s. But it was actually transmitted by the fleas of warm-blooded mammals in general. Rats appeared responsible for the plague only because they were so common.
This was also during an era when our most scientific explanation for disease was some sort of divine punishment or witchcraft, and mankind had neither the facilities nor interest in washing their damn hands. Now obviously bubonic plague isn't a problem these days, and you'll be hard pressed to find a rat-spread disease that is. According ot the Center for Disease Control, rats don't even spread rabies.
That's right, despite their absolutely staggering numbers, rats are one of the animals you're least likely to get sick from.