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  • Karin Lindquist

What's the Point of Mosquitoes?

The despair in their voices was palpable. "Terrible, just terrible. I couldn't believe just how much bug spray I had to use on those nasty little b*ggers!"

I just couldn't resist asking them how bad the mosquitoes were. It's... both for entertaining and educational reasons.

But hey, it feels good to complain about something we can't control. Like the weather. Or... the mosquitoes. It's a great way to start a conversation or break the ice with a total stranger. So, I have to ask.

But, when I open the floor to lamenting about these insects, I also open up the opportunity for a topic to write about. Often that topic comes in the form of a rhetorical question.

For some reason this summer, multiple people postulated this very question (posed in the title). Even on one of our nature walks a member of ours couldn't help but state it out loud. Perfectly understandable.

So, I had to write about it. Mosquitoes are a part of nature after all. Just like snakes and spiders and other creepy crawlies or whiny flying things that freak some of us out...

I have to say: what I found out about this little creature turned out to be nothing short of fascinating.

Name the Most Annoying Insect on the Planet...

You all know the answer. Yep, mosquitoes.

The thought of facing these tiny, blood-sucking insects can make most people second-guess almost any activity outdoors.

The sound that their tiny little wings make is almost like nails on a chalkboard. One buzzing around your head is mildly annoying. I might be speaking for myself on that, though.

But when hundreds of them descend upon you in eager anticipation of fresh blood is not only irritating but to the point of being terrifying. It'll make anyone go diving into their bag for the bug spray...

Or, lament and complain about not forgetting to bring some.

Or, at the very worst, turn tail and run back to the safety of the car (or house) and swear to never venture outdoors ever again!

I'm sure you have wished over and over again that mosquitoes never existed. Many of us have also thought that the existence of these tiny creatures is only to annoy the heck out of us every time we have to be outdoors in the summer. Or any vertebrate for that matter.

Yet, mosquitoes exist. But I do not believe that they exist just to be an irritant to use a full can of bug spray on. (Or for a city or town council to approve the use of insecticides on in various urban wetland ecosystems in the past...) No, there's a very good reason why these little insects are needed in the natural ecosystem.

But first, a disclaimer: This post is by no means a means to tell you to put away the bug spray. For your own sanity, and to enjoy the outdoors, please use it. This post is only to help you (hopefully) better understand the purpose of mosquitoes in any natural habitat and to maybe better appreciate their existence.

The Ancient "Little Fly"

According to Wikipedia:

Mosquitoes... are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin culex meaning "gnat"). The word "mosquito" (formed by mosca and diminutive-ito) is Spanish and Portuguese for "little fly".

Amber containing fossilized mosquitoes date their existence back to the Early Jurassic era of almost 200 million years ago.

So, apparently, mosquitoes have been around for much longer than we have. And they even pestered the dinosaurs!

There are 112 genera of mosquitoes in the world. In Canada, there are only about 10 genera of mosquitoes that have so far been identified. Click here to find a dichotomous key to mosquito species of Canada.

Of these genera, only a few have been made infamous for the parasitic and arboviral diseases they've spread, which have killed thousands of people. Malaria, yellow fever, dengue fever, and especially in North America, the West Nile virus have made the mosquito into the infamous bug it is.

The fact that mosquitoes are one of the most feared bugs makes it easy to justify wanting to kill every single one of them and question the very purpose of their existence.

So, what purpose do mosquitoes actually serve??

Mosquito Ecology

Did you know that Iceland is the only country that has no mosquitoes? That's right. Except in Antarctica, mosquitoes are found all over the world. The reason is that most places have the right environment and conditions to support and complete the life cycle of the mosquito, from breeding to emerging from the pupal stage.

The reason that Iceland and other areas with similar environmental conditions do not support mosquitoes is that the weather conditions are too unpredictable. Weather can bring in freezing temperatures at any time, rather than in more predictable patterns like in most of mainland Americas and Eurasia. Mosquitoes, according to my research, seem most vulnerable at the pupal stage in such areas and emerge after the ice breaks and winter releases its clutch from the northern landscape. In Iceland, freezing temperatures can come back at any time and remain long enough to kill the insect still in its late pupal form.

Now, before you decide you should move to Iceland, they still have their less infamous bloodsuckers: the black flies. Black fly eggs and larvae can survive in running water and under stones where it does not freeze, which is completely counter to what mosquitoes need for survival.

Any source of standing, stagnant water that can last long enough for mosquito eggs to hatch into larvae, provide food for the larvae and host this insect during its pupal stage is sufficient for the mosquito. Generally, this means a period anywhere from 20 to 60 days, from hatchling to laying and death.

However, these insects will go into a period of "diapause" if conditions become unfavourable for life to continue, such as when there is a long period of drought, or when winter arrives and remains for several months. This can be at any stage. Once conditions become favourable, they basically pick up from where they left off and continue their life cycle again. Not all species have this ability, thankfully.

I realize I'm still evading the question of what purpose mosquitoes serve. I'm getting there!

The question starts with a look at who feasts on who. What's fascinating about the mosquito--at least to me--is that only the females are the hungry blood-suckers. The males are not.

I've briefly looked into why this is, and the only explanation is that blood from any vertebrate provides enough nutrients to support egg and larval production. Blood contains plenty of amino acids, fatty acids, water, and other nutrients needed to grow eggs.

The males don't need such a wealth of nutrition, so they feed off of nectar and sap from plants. Some female mosquitoes do this as well, at least until they need to feed on blood to support their eggs.

What about their offspring? Larvae actually feed on bacteria, algae, and fungi that exist in the stagnant water they live in.

Here's a neat DYK: Females mate only once, but will lay at least 50 to 100 eggs or so every three days, or at least that's what Google says. Male mosquitoes will mate several times before they die.

Or get eaten.

Mosquitoes Feed Others

The whole purpose of mosquitoes is...

To feed other animals!

Mosquitoes, both in adult and larval stages, get eaten by a wide variety of animals, thankfully! For birds, many migratory species including hummingbirds, flycatchers, purple martins, terns, swallows, sparrows, titmice, warblers, ovenbirds, and thrushes love eating mosquitoes. Non-migratory birds like chickadees might also eat the occasional mosquito.

Bats love mosquitoes too! A 2006 study by Rydell et. al. (Journal of Zoology) has shown that little brown bats have a 92% effectiveness at catching and eating mosquitoes. (Great reason to put up a bat house or two around the yard, eh?)

What about other bugs? Dragonflies, damselflies, and spiders will certainly catch and eat mosquitoes. Nematodes also eat mosquitoes, especially when in larval and pupa form.

We often believe that frogs and toads also predate on insects like mosquitoes too! However, a 1997 study in Germany found that the frogs in their area included less than 1 percent of mosquitoes in their diet. That is because of the time of day amphibians are most active compared with mosquitoes. Where mosquitoes are diurnal (prefer the daytime), frogs are much more nocturnal or crepuscular, preferring prey that comes out during at night.

Larval mosquitoes are also eaten by a variety of organisms, including minnows, dragonfly and damselfly larvae, turtles, salamanders, and juvenile waterfowl. Tree swallows apparently also eat mosquito larvae when they can as well.

Let's not forget aquatic beetles like diving beetles and water scavenger beetles which basically will catch and eat anything that moves.

Oh yes, and what about fish? Besides mosquito fish (minnows, basically), other fish like bass, bluegill, perch, and some trout (especially as young fish and/or species that prefer warm, slow-moving to still waters) will prey on mosquito larva without hesitation. Non-native fish that we might throw in isolated ponds that also eat these tiny wrigglers include koi, goldfish, and guppies.

You might say that mosquitoes get their "karma" by being eaten by a wide variety of predators. I think we should all be thankful that despite they're being vectors for disease, they're definitely not apex predators.

In Summary: We Need Mosquito Predators to get Fewer Mosquitoes

I get the complaints, I really do, because I'm just as guilty. I also understand that there are many quick-fix "solutions" out there to kill off as many mosquitoes as possible as fast as possible are used to counter the (forgive my facetiousness) "mosquito-pocalypse."

But I believe that a less from Nature is to be learned here. Quick-fix solutions like dish soap in water or insecticides quickly destroy any opportunity for a variety of predators to take advantage of the sudden abundance of these blood-thirsty "little flies." If we want to enjoy more birds and bugs, we should provide both the habitat they need plus the prey they need to live there.

Yes, that may mean putting up with those annoying mosquitoes.

Yet, it helps us appreciate the value mosquitoes bring to the greater ecology. It's amazing all the critters they feed.

Certainly, something to consider as you absent-mindedly scratch that mosquito bite on your ankle...

As I just had to.

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