Giant mosquitoes are invading my backyard!

“I’ve never seen anything like it. I actually heard it before I saw it!”

I get more than a dozen emails, tweets, or phone calls every summer like this. Excited (terrified?) correspondence asking about the “giant” mosquito captured in the backyard or buzzing about windows.

Toxorhynchites speciosus is as “good” a mosquito as there can be. First, it is a gorgeous creature. Almost four times the size of a typical mosquito, it is a large dark and shiny mosquito with bright metallic patterns.

There are around 70 species of Toxorhynchites mosquitoes around the world but only a few species found in Australia. The mosquito is reasonably common, but rarely very abundant. It is found along the eastern and north coast of Australia, stretching from Sydney through to Darwin.

The larvae of Toxorhynchites speciosus are large and easily spotted in water-holding containers around the backyard

This is one of the few mosquitoes that don’t need blood. Unlike almost all other mosquitoes, the females of which need blood to develop their eggs, Toxorhynchites speciosus doesn’t bite. It gets its energy from plant juices and nectar.

Even though it doesn’t bite, the sheer size of this mosquito makes it an imposing sight.

They most commonly lay eggs in water holding containers around the home. Pot plant saucers, bird baths, watering cans, buckets, bins and even tree holes and water-filled bromeliads. These are the same types of water-filled containers where you’ll find wrigglers of the pest mosquitoes Aedes notoscriptus and Culex quinquefasciatus.

They have a fascinating way of laying eggs. Unlike many other mosquitoes that elegantly stand on the water surface and lay up to 300 eggs in a neatly packed floating raft, Toxorhynchites lays single eggs. It  doesn’t even land on the water to lay eggs, it fires them into water while in mid flight!

Once an appropriate place to deposit an egg has been identified, the mosquito flies in a vertical loop, the loops getting ever smaller until the egg is ejected and into nearby habitats. A neat trick and avoids the risk of being eaten by a hungry spider or other predator waiting by to grab a mosquito coming in to lay eggs.

A specimen of Toxorhynchites speciosus collected by Helen Mamas from the inner west suburb of Sydney, Newtown

Not only do these mosquitoes not bite, they even help out with a little pest mosquito control around the home.

While the mosquito wrigglers of mosquito mosquitoes feed on organic debris floating about in water bodies, the larvae of Toxorhynchites speciosus are predatory and feed on the wrigglers of other mosquitoes. Laboratory studies have shown that a closely related Toxorhnychites consumed over 300 Aedes aegypti  (aka the dengue mosquito) larvae during its development. In some parts of the world, a closely related mosquito is used as a biological control agent of the pests that spread dengue, chikungunya and Zika viruses.

While Toxorhynchites speciosus will chomp through plenty of wrigglers of Aedes notoscriptus each summer in Australian backyards, it is unlikely to make a huge difference in bites.

My experience in backyards across Sydney has shown that there is something of a tug-o-war between Toxorhynchites speciosus and other mosquitoes. While undertaking a project with Ku-ring-gai Council looking at backyard mosquitoes and their possible impact on backyard wildlife conservation efforts, I’d often find a fluctuating dynamic between the mosquito predators and their prey. Populations of Aedes notoscriptus or Culex quinquefasciatus would build up in bird baths and buckets, then Toxorhynchites speciosus would move in. They’re eat through all the other larvae, then once emerged and flown off, the other mosquitoes would move back in. And the cycle continued.

Image of Toxorhynchites speciosus sent to be by David Lawson from the inner west suburbs of Marrickville, Sydney.

Next time you see a “giant mozzie” buzz by, think twice before you squish it. Oh, and keep in mind that this mosquito is also a movie star! Do you recognise it from Jurassic Park?

If you want to keep the pest mosquitoes out of your backyard, make sure you get rid of any water-holding containers. If you can’t throw them out, keep them covered.

Check to make sure your roof gutters and drains are clear of leaves and other debris so they flow freely. Check your rainwater tank is screened to stop the mozzies entering. And try not to kill the good guys who help keep the other mozzies at bay!

For more on how to better control insect pests in and around the home, read one of our latest publications on engaging urban stakeholders in the sustainable management of arthropod pests.

Find out more about Australia’s fascinating mosquitoes by checking out our “A Guide to Mosquitoes of Australia” via CSIRO Publishing!

 

Dinosaurs, DNA, Mosquitoes and Movies

I thought I’d celebrate the 20th anniversary of one of my favourite movies, Jurassic Park, by posting on, what is arguably, the most famous mosquito in cinematic history.

As most people probably already know, the “science” of the story revolves around the cloning of dinosaurs from DNA samples obtained from prehistoric mosquitoes. The DNA was purportedly extracted from blood meals contained within these mosquitoes that had been trapped and preserved in amber. Even though studies have suggested that DNA wouldn’t survive long enough to assist in making “Jurassic Park” styled dinosaurs a reality, modern molecular techniques are quickly improving and may make the impossible a little more possible in the future.

If we can improve the technology enough to make this happen, could the research team who receives the multimillion dollar grant please go to the trouble of hiring an entomologist? You don’t want to make the same mistake as the team led by entrepreneur John Hammond.

I’m not just referring to the creation of nasty people eating dinosaurs. If you’re hunting around for mosquitoes in amber, you’d better pick the specimens that may actually contain blood!

The screen shot above is taken from a scene in the movie (see YouTube clip below). The scene provides some background to the process behind dinosaur DNA capture. It has already been pointed out elsewhere that the mosquito specimen depicted in the video is a male mosquito. Male mosquitoes don’t feed on blood.

Only female mosquitoes feed on blood, they need the nutritional hit to develop their eggs. Mosquitoes take blood from a range of vertebrates. Birds, mammals, frogs and reptiles. In theory, there is no reason why a mosquito wouldn’t bite a dinosaur. Blood meal analysis of mosquito populations in Florida during an outbreak of West Nile virus revealed that a number of mosquitoes were feeding on alligators (Alligator mississippiensis).

The problem isn’t just that the mosquito depicted in the video is male, the type of mosquito shown doesn’t feed on blood at all!

Not all mosquitoes need a blood meal. There is a group of mosquito species that belong to the genus Toxorhynchites. These are large, very beautiful mosquitoes that often have a metallic appearance. They are really the “good guys” of the mosquito world. Their immature stages are predatory. They are typically found in natural or artificial water holding containers such as buckets, bird baths, tree holes or discarded tyres. They tend to move in and eat through some of the other pest mosquitoes found in these types of habitats such as Aedes aegypti and Aedes albopictus. These mosquitoes spread pathogens such as the dengue and chikungunya viruses.

Notwithstanding their size, a Toxorhynchites is most easily identifiable by their long bent proboscis. Compare the photo below to the screen shot from the Jurassic Park video. See that bent proboscis? The bent proboscis assists in nectar feeding by this mosquito. (as an aside, if you look at the shot of the “Jurassic Park” mosquito, you can see that the wings of the mosquito are actually squished down along the side of the abdomen. The “wings” shown in the mosquito are fake. There are no wing veins)

Taken from the archives of the Walter Reed Biosystematics Unit

Lets give credit to John Hammond and the team at International Genetic Technologies, perhaps it is samples from these mosquitoes that they were able to use to clone the prehistoric plants that were growing throughout Jurassic Park?

If you’ve decided to go out and hunt down some dinosaur DNA, best look out for mosquitoes that actually feed on blood!

Do we know that mosquitoes were even buzzing about with the dinosaurs?

There is strong evidence, both preserved specimens in amber as well as fossils, that mozzies have been about since at least the Cretaceous Period. A paper by Poinar et al. (2000), in their description of a small mosquito named Paleoculicis minututs from a sample of Canadian Cretaceous amber, provides references to almost 40 references to mosquitoes in the fossil record. Paleoculicis minututs was thought to have dated back to 66-100 million years ago but the oldest known record of a mosquito is Burmaculex antiqus described from Cretaceous Burmese amber (89.3-99.6 million years ago).

Recently, two new mosquito species, Culiseta kishenehn and Culiseta lemniscata, were described from compression fossils in shale deposits dating from 46 million years ago. These fossils are pretty amazing as many of the morphological features we use to identify mosquitoes, such as scales and wing veins, have been preserved.

Mosquito fossil of Culiseta lemniscata  Smithsonian’s National Museum of Natural History

There are mosquitoes related to these two species flying about today. There are thought to be almost 40 species belonging to the genus Culiseta. They’re generally considered to be associated to cooler-temperature climates. We have a few species in Australia such as Culiseta frenchii, Culiseta hilli, Culiseta inconspicua and Culiseta litteri. They tend to be associated with ground pools in forested areas. Although they will bite humans, they are rarely considered pests and have not been associated with the transmission of pathogens locally. However, related species are thought to transmit both Eastern and Western equine encephalitis virus in North America. Mosquitoes belonging to Culiseta, although they will bite mammals, are generally thought to prefer blood meals from birds.

Culiseta morsitans taken from Walter Reed Biosystematics Unit

While it may be fun (and nerdy) to spot mistakes like this in movies, it is nice to be given an opportunity to dig back through the literature and have a closer look at some of the more unusual mosquito species and their place in the fossil record. Perhaps we’ll find some mosquitoes in Australian fossils someday too. I’m not aware of any mosquitoes identified from fossils found in Australia but there are research projects investigating insect specimens in amber. Fingers crossed.

UPDATE. Wouldn’t you know it! Just as I hit “publish”, I notice that a similar story is doing the rounds today, something must be in the water!!! Joe Conlon has been reported in a few places reporting the same issue. Some more coverage here.

UPDATE [15 October 2013]. Some more “mozzie fossil” news is making headlines today with the fossil of a blood-engorged mosquito in oil shale from northwestern Montana, USA, has been described in a recently published paper!

Newly described blood-filled mosquito fossil (The National Museum of Natural History, Washington via Nature)

The discovery of a mosquito (Culiseta sp. Culicidae) fossil clearly displaying an engorged abdomen from a recent blood meal has provided more evidence that mosquitoes were feeding on vertebrates as far back as 46 million years ago. Not only does the specimen look engorged, mass-spectrometry analysis of the specimen identified heme, the oxygen-carrying group of hemoglobin in the host’s blood. The study, publish in Nature, describes the discovery but also details the “extremely improbable event” that this fossil was created, let alone discovered tens of millions of years later!  While discoveries like this still aren’t going to bring back the dinosaurs, they do confirm hematophagy in the fossil record. I wonder what other specimens are out there?

Update [1 December 2014] Jurassic World repeats the mistakes of the past…

A screen shot from the Jurassic World trailer…is this supposed to be a mosquito?

November saw the release of a trailer for the new movie in the “Jurassic” franchise, Jurassic World. As well as attracting plenty of attention from fans and media about the movie, it also attracted plenty of interest from dinosaur lovers and entomologists. There was a great post by Dr. David Steen on some of the errors spotted by wildlife biologists and paleontologists and Morgan Jackson put together a nice piece on the entomological inaccuracies of the trailer (it is a crane fly, not a mosquito, locked up in that amber). Despite all of this, perhaps the biggest issue to have arisen is the purported unauthorized  use of illustrations in accompanying promotional material.

“Shut up, Scientists! Always have to ruin everything with facts and accuracy.”

It would be silly to get REALLY upset about the mosquito/crane fly mix up but there was no shortage of people pointing out the mistake, you’d think they’d fix it this time around (unless there is a gag we’ll get in the movie about crane flies and non-biting mosquitoes). However, any opportunity to point out some scientific inaccuracies provides an opportunity to raise awareness of genuine scientific knowledge. I’m regularly called up to investigate “giant mosquito” problems….that almost always turn out to the crane flies (they don’t bite BTW).

I’ll be heading along to see the Jurassic World monsters in 2015 but perhaps I’ll take the kids back to the museum to learn about dinosaurs and some of the other extinct Australian mega fauna for a hit of real science.

Now, about that light saber in the trailer for “The Force Awakens”….