In a time of rampant political and ideological polarity, I see it as my duty to our society to invite nuance and complexity to the table. The entomological table at least.

“What is the purpose of mosquitoes?”

“Can’t we just invent a technology to wipe them all out?”

“What would even happen if we got rid of them?”

“Do those mosquito repellent stickers work?”

I’ve been asked these questions multiple times by multiple people throughout my time as an entomologist and only one can be answered with a yes or no. You’ll have to read the rest of my article for that answer though.

A brief pause to note that the major problem with three out of four of these questions is that pesky thing, the human ego, that has us centering ourselves as the sun in our ecological solar system. Just because we are the most destructive species, does not necessarily make us qualified to decide which of our fellow organisms deserve to be deleted or not. But, egocentric creatures that we are, we like to justify our approval or distaste for other creatures by measuring their impact on us.

So, sure, no one likes being bitten by mosquitoes. They carry and cause a lot of significant human disease, including malaria, the disease that continues to be the leading cause of preventable illness and death worldwide. BUT, mosquitoes as a group (like all organisms on earth) hold ecological function. AND, not all mosquitoes bite humans. Male mosquitoes feed on flowers, not blood, and thus they play a role in plant pollination. AND, mosquitoes are also an important food source to a variety of animals including but not limited to amphibians, birds, bats and other insects.

Now, to unsuspectingly lure you into appreciating mosquitoes… Well, one group of species at least.

Introducing: elephant mosquitoes! Otherwise known by their scientific name: Toxorhynchites.

Toxorhynchites (toxo-rin-KIE-tees) are not named elephant mosquitoes because they feed from elephants, but their common name stems from their large size relative to other mosquitoes. The group boasts the largest mosquito species in the world at nearly two centimetres in length, roughly four times the size of other mosquitoes. Another fun taxonomic trait is their peculiar curved proboscis, which is the needle-like mouthparts used to pierce skin and suck blood, or in the case of Toxorhynchites, feed on sap and flower nectar.

Yep, you heard correctly. In this group of mosquitoes, both the daddies and the mummies eat flower nectar. Despite their menacing appearance, these humongous mosquitoes will not come buzzing for your blood.

Not only that, Toxorhynchites larvae dine on other mosquito larvae, including the mosquito species that do bite humans. Studies found that Toxorhynchites consume from 300 to 5000 mosquito larvae during larval development¹. Not only that, Toxorhynchites exhibit a pre-pupal murderous rampage, where they attack and kill a large number of mosquito larvae without consuming them².

All that bloodthirsty, carnivorous behaviour in their larval form means that the protein requirements for reproduction are met before pupation and adult emergence, allowing the adults to skip the steak and enjoy a vegetarian lifestyle. As a result, these mosquitoes are not just benign but beneficial to human life. They are caught in a somewhat unhealthy symbiotic relationship with us, in that we benefit from them without them even knowing they are in a relationship. The ethics of informed consent among humans and mosquitoes aside, their use in pest mosquito control has been explored and in some regions they have been utilised as biological control.

Many studies overseas have proven the effectiveness of Toxorhynchites larvae at wiping out the larvae of Aedes aegypti, otherwise known as the yellow fever mosquito. Besides yellow fever, this mosquito also transmits Zika, chikungunya and dengue fever, and the control of its population in endemic regions is vital in limiting human disease and mortality. There are about 70 species of Toxorhynchites worldwide but only a handful exist in Australia, the most common of which is Toxorhynchites speciosus.

This homegrown elephant mosquito has proven itself effective at reducing common nuisance species including Aedes notoscriptus and Culex quinquefasciatus, both of which breed in water containers and are extremely common in Australian backyards³. So you see, these friendly giants might appear shocking, but you would be blessed to find one emerging from your frog pond.

While we are on the topic of mosquito misrepresentation, Toxorhynchites is arguably and ironically the most famous mosquito (at least cinematographically) after being featured in Jurassic Park, stuck in a block of amber. If you don’t remember, the mosquito is the key to re-aliving the dinosaurs by extracting DNA from dino blood within the mosquito. The misrepresentation is two-fold: firstly, the mosquito they picked is male and no male mosquito feeds on blood; and secondly, the females of this group don’t either! I am a really fun person to watch sci-fi films with. I'll pick out and ridicule all the scientific inaccuracies until the film loses all its appeal for both of us.

If there is one message I want to transmit here, it’s that not all mosquitoes are scheming to make your life hell, some actually help us.

And no, those repellent armbands do not work to protect you from mosquito bites, don’t get sucked into the hype⁴. If in doubt, use something containing DEET; otherwise Picaridin and oil of lemon eucalyptus have been shown to be effective too, depending on the concentration⁵.

Further reading

My PhD supervisor and mosquito extraordinaire Dr Cameron Webb writes a mozzie blog where you can get your fix of mozzie facts and info.

References

1. Steffan, W.A.; Evenhuis, N.L. (1981) Biology of Toxorhynchites.Annual Review of Entomology 26, 159-181.
2. Collins, Larissa & Blackwell, A.B. (2000). The biology of Toxorhynchites mosquitoes and their potential as biocontrol agents. Biocontrol News and Information. 21. 105-116.
3. Brown M.D., Hendrikz J.K., Greenwood J.G. and Kay B.H. (1996). Evaluation of Mesocyclops aspericornis (Cyclopoida: Cyclopidae) and Toxorhynchites speciosus as integrated predators of mosquitoes in tire habitats in Queensland. J Am Mosq Control Assoc.12(3 Pt 1), pages 414-420.
4. Revay EE, Junnila A, Xue RD, Kline DL, Bernier UR, Kravchenko VD, Qualls WA, Ghattas N, Müller GC. (2013). Evaluation of commercial products for personal protection against mosquitoes. Acta Trop.125(2):226-30.
5. Webb, C.E., Hess, I.M.R.. (2016). A review of recommendations on the safe and effective use of topical mosquito repellents. Public Health Res Pract. 26(5)