“What is their purpose?”

The idea what any form of life needs a ‘purpose’ is out of line with how the natural world works. If there is an opportunity to survive there is something adapted to this opportunity. Survival/Life is their purpose. In a broad sense all species have simply adapted to fulfill an available ecological niche.

(The eminent biologist Ernst Mayr makes a powerful argument against this kind of teleology.)

Mosquitoes

Blunt-leaved Bog Orchid - Platanthera obtusata

By Gary Van Velsir. Copyright © 2022.

Mosquitoes are commonly considered nuisance insects. For their eggs to successfully develop into larvae female mosquitoes must provide them with a source of protein; this protein acquired in the form of blood. Although all warm blooded creatures (mammals and birds) are fair game, our thin and relatively hairless human skin is especially appealing as an easy meal. When mosquitoes aren't blood feeding to support the development of healthy eggs, the adults feed off of plant nectars to fuel their flight. Of the 3,500 species of mosquitoes, only the females of 6% of those species bite humans.

While nobody likes mosquitoes they play a huge role is our ecosystem. Theyre a huge source of food for fish, small aquatic animals, dragonflies, bats, birds, and many many other creatures (some animals preying exclusively on mosquitoes). Believe it or not, they pollinate plants, as they feed from flower nectar (certain orchid species are pollinate solely by mosquitoes).

Most people think of mosquitoes only as insects that suck blood, but they have another niche in the ecosystem–they pollinate flowers. Many mosquitoes around the world pollinator small flowers!

Mosquitoes act as pollinators for grasses and a few other flowering plants. Their role in spreading pollen hasn’t been studied nearly as much as their role in drinking blood and spreading diseases. But the niche they’re best known for is pollination orchids, including the Blunt-leaved Bog Orchid (Habenaria obtusata, also called Platanthera obtusata), and other rare Arctic bog orchids.

Cockroaches

There are more than 4,000 species if cockroach, only 4 of those species are considered a nuisance to humans.

Cockroaches feed upon decaying organic matter, leaf litter and wood around it. Not only do they help “clean up” degrading plant material, in the process their bodies trap a lot of atmospheric nitrogen. They’re also a food source for many small animals like squirrels, birds, mice, etc.

Madagascar Hissing Cockroaches - *Gromphadorhina portentosa*

By: Sarah Folts - The Butterfly Babe

Furthermore, some insects rely on cockroaches exclusively for their survival. Among these are the parasitic wasps, which specialize in feeding off cockroach eggs. The disappearances of roaches would cause this wasp to go extinct.

Roaches have been used in medicine throughout history. When ground up, they can treat ulcers and are continuously studied to find links to other treatments. A study published in Pathogens and Global Health explored the viability of using roaches as modern medicine. It explored the resiliency of these pests to learn how to repel bacteria and diseases better. As a test, scientists ground up different parts of cockroaches and exposed the tissue to bacteria. When the bacteria reached any tissue from the brains and nerves, the scientists noticed that the bacteria were killed. That leads many to believe that cockroaches’ brains will be essential in killing things like E. Coli and MRSA. Theyre also used in robotics labs to help better develop prosthetics

Spiders

Spiders live in almost every habitat on the planet, so it’s not unusual to find them in the forest or near the sea. And while spiders might make some people cringe, hopefully you’ll find them fascinating after learning a little bit more about how important they are to the earth’s ecosystems.

There are more than 45,000 known species of spiders, found in habitats all over the world. 3,700 species of those spider are found in the US and only about a dozen are considered medically significant. The vast majority of spiders are harmless and serve a critical purpose: controlling insect populations that could otherwise devastate crops. Without spiders to eat pests harmful to agriculture, it’s thought that our food supply would be put at risk.

Spiders feed on an estimated 400 to 800 million tons of insects and other pests annually; in comparison, all humans consume about 400 million tons in meat and fish. It is estimated that one single spider can eat as many as 2,000 insects in a year. They eat many insects that pester or even harm humans, including mosquitoes that can transmit deadly diseases like Zika virus, West Nile virus, malaria, dengue, and yellow fever. In fact, two species of jumping spiders, Evarcha culicivora and Paracyrba wanlessi, are known as “mosquito terminators,” preferring to eat mosquitoes over other prey.

Ticks

These tiny pests aren't without importance. They benefit the moist, dark ecosystems in which they live by serving as a food source for many reptiles, birds and amphibians. They also help control wild animal populations. Scientists even use them as an indicator of an ecosystem's overall health and stability. Found throughout forests and grasslands in North America and Europe, these annoying little critters do serve a purpose.

Humans who think about diseases are often trying to prevent or cure them. Like ticks, however, disease serves an important role. Disease helps to control wildlife populations while weeding out the weaker animals, preventing them from passing on potentially flawed traits. Nature is all about survival of the fittest, and disease helps determine which animals are, in fact, the fittest.

Ticks carry Lyme disease, Rocky Mountain spotted fever and tularemia, all of which have a big influence on the health of animal populations within an ecosystem. Without these diseases and the ticks that spread them, an area could find itself overrun with deer, rabbits, mice and other animals who otherwise would have become ill and died.

Fleas

These blood-sucking parasites are vectors for pathogens. They help spread disease to re-balance populations that are out of control. For example, The black death (bubonic plague) was spread by fleas, they were an essential link in the chain of events that resulted in the death of a quarter of the population of Europe.

Some fleas (e.g., shrew fleas and rabbit fleas) are highly host-specific, whereas other species parasitize a variety of mammals. The cat flea infects not only the domestic cat but dogs, foxes, civets, mongooses, opossums, leopards, and other mammals, including humans, if its regular hosts are not available. Bird fleas have adapted themselves in relatively recent times to their avian hosts.

It is interesting that monkeys and apes do not harbour fleas, nor do horses or the majority of ungulates. The most heavily parasitized group of mammals are the rodents (e.g., rats, mice, squirrels). Their habit of nest building in holes favours development of flea larvae. Animals with no permanent home tend to have fewer fleas.

wasps

Wasps have generally earned themselves a bad reputation. But despite their occasional aggression, these insects play an important role in the ecosystem. They are actually very important in keeping the ecosystem balanced. Wasps are generally apex predators — so, if they're not doing well, it indicates that there is something wrong with the world. Wasps are hugely beneficial to their native ecosystems due to the sheer amount of insects they capture.

Adult wasps don't eat the prey they kill - they feed it to their young. Social species capture insects, chop them up and carry parts back to the nest. Some solitary species are more sinister. For example, most spider wasps paralyse arachnid prey using a venomous sting. Their larvae then eat the victim alive.

Instead of eating insects and spiders, adult wasps - both social and solitary - only feed on sugars. In the wild, sugars come from flower nectar and honeydew produced by aphids. When on the hunt for nectar, wasps also become pollinators by travelling from plant to plant carrying pollen. While their contribution to pollination may not be as substantial as bees, wasps still play a valuable part.

Wasps prey on other insects, which means they serve as a means of natural biocontrol to protect crops. That service alone is worth at least $416 billion a year around the planet in agriculture because wasps regulate populations of arthropods, like caterpillars that feed on crops.

Why Do They Exist?