Significance of insects and other creepy crawlies
Above: It looks like it wants a hug! (Oxytate virens, green crab spider)
Imagine waking up in a world where there were no insects, arachnids (spiders and scorpions) and myriapods (millipedes and centipedes). That means no mosquitoes to irritate us and spread deadly diseases, no cockroaches scurrying across your kitchen floor when you turn on the lights, and no spiders taking refuge in your cellar. That sounds great doesn't it? Except that in a world like that, we humans would probably be struggling to survive.
Why would we suffer without these creepy crawlies you might ask? Well, these creepy crawlies happen to provide many beneficial services to the ecosystem, and to us humans.
1) Pest control
The phrase "fight fire with fire" can be slightly altered to "fight bugs with bugs". And this phrase quite aptly describes the efficacy of using predatory arthropods like ladybirds, wasps, centipedes and spiders to combat plant pests like mealybugs, aphids and grasshoppers. Without our beloved predatory bugs doing their jobs, our job of growing food and maintaining pretty gardens would be much harder. More pesticides would have to be sprayed and that can't be very good for us or the environment, given how pesticides are toxins designed to kill.
Mother Nature throws at every single organism its Kryptonite, and that includes many pests in the city. Mosquitoes? Dragonflies, damselflies and spiders happily munch on them. Cockroaches? Centipedes and large spiders come to the rescue. Houseflies? The hungry mantis on the nearby shrub would like to slay them.
One reason why insects like mosquitoes, cockroaches and houseflies are able to thrive and cause us problems in our city is because many of their natural predators, which happen to be creepy crawlies as well, are not encouraged in our spaces. Getting rid of native greenery, excessive use of pesticides and just the general urge felt by many humans to get rid of any and every bug can all have adverse effects on predatory bug populations.
Above: Damselflies such as this blue damselfly (Pseudagrion microcephalum) do us a huge favour by consuming large amounts of those annoying mosquitoes.
2) Pollination
Another crucial service of creepy crawlies is pollination. Many plants depend upon insects to pollinate their flowers, and thus, to set fruit. Without pollinators like bees, butterflies and flies, many crops would have to be hand-pollinated by farmers. That would be a lot more hard work! The next time you enjoy a mango pudding or some fruit juice, know that what you are consuming would probably be a lot more costly to produce if not for the helpful insect pollinators' tireless visits to the flowers.
3) Decomposition
Humans often frown upon the maggots that ravage a putrefying corpse, or the cockroaches that roam the dumpsters in search of food. But without these decomposers or more specifically detritivores, our world would be knee deep in faeces and food waste. Detritivores include various flies, millipedes, beetles and cockroaches. These arthropods break down dead plants and animals into smaller parts, which increase the rate of decomposition of organic material into finer compost. While decomposition would still continue without the presence of the invertebrates, due to the bacteria and fungi that are responsible for the process, it would take a whole lot more time to proceed in the absence of the detritivores.
Above: Millipedes (here, Trigoniulus corallinus and Leptogoniulus sorornus) are important to the recycling of nutrients. Without them, we'd see a lot more recognisable dead stuff.
4) Production of various materials
Humans depend on many arthropods for utility and food. Silk moths (Bombyx mori) produce the silk that we use to make clothes. Honey comes from honey bees (Apis spp.). The prospect of using spider silk for armour is interesting and potentially beneficial to humans too. Some researchers in the medical field have also taken interest to certain sawflies' ovipositor, a long organ used to deposit eggs, which is very precise and could inspire the creation of improved surgical tools.
Entomophagy, or consumption of insects, is also not an uncommon practice in some human cultures. Cockroaches, grasshoppers and spiders are eaten and they are actually not a bad source of protein. In fact, entomophagy may be necessary in the future due to the issue of production of meat. In other words, insects may become a more sustainable alternative food source to the beef or mutton that we enjoy so much today.
Above: Imagine consuming this Javanese grasshopper (Valanga nigricornis). Well it might become a reality in time to come!
5) Link in the food chain
Insects and other arthropods are food not only for each other, but also to many other animals that are useful to humans. For example, chickens get a significant amount of nutrients by ingesting insects, and many fish too are insectivorous. Insects are also reared for fish feed or chicken feed. For example, black soldier flies (Hermetia illucens) are reared for their gregarious maggots, which are fed to fish and chickens due to their high protein content.
Conclusion
Insects, spiders and other arthropods play a very crucial role in our economy, environment and general well-being. While there are definitely some of them that can cause considerable damage to us, a super majority of species are harmless or beneficial to us. Humans are dependent on insects, mostly indirectly but in some cases directly, and a world devoid of these little buggers would be one that I would not like to even think about.
Above: Just take a moment to take in its beauty. (Junonia almana javana, Peacock pansy)