Wednesday, September 2, 2015

Elephant Mosquito Returns

Back at Blue Jay Barrens after a five year absence, by popular demand, it’s the Elephant Mosquito, Toxorhynchites rutilus septentrionalis.  A behemoth of the mosquito world, this non blood sucking species is the largest mosquito to be found in North America.  I found this larva, posing beside its normal sized relative, living in a tub of water beside my house.  This is a southern species whose range extends into the lower half of Ohio.  It’s possible that the species has trouble surviving Ohio winters.  If so, the Ohio population would depend upon more southern populations moving north each year to recolonize this area.

Elephant Mosquitoes are predators, feeding on small aquatic organisms.  Its diet consists primarily of the larvae of other mosquito species. 

Eating is the primary activity of the Elephant Mosquito larva.  This one is consuming a double helping at one time.  The larval stage can last from a few weeks up to several months.  I’m sure that temperature affects the rate of development, but I would guess that the available food supply is also a critical factor.

Even though the larva will grab prey whenever presented with the opportunity, most of the active hunting seems to occur at the water’s surface.  Floating with a collection of potential prey items, the larva will raise its body into a horizontal position and slowly reach out towards its prey.  When it gets within range, it give a quick lunge and grabs the prey with its strong set of mandibles.  I watched this individual, which is now housed in a small aquarium, consume six mosquito larvae in 20 minutes.  It has since greatly slowed its rate of consumption.  I believe my supplying the Elephant Mosquito with a density of food items about 25 times greater than what it was used to might have been the cause of the initial glut.

This is typically a tree hole species that breeds in water pockets trapped inside tree cavities.  I imagine one of these predators could easily clean out the mosquito population in a small pool.

The Elephant Mosquito larva is primarily an eating machine.  Fortunately, the large sized adults feed on nectar and other plant juices, so are no threat to people.  Click HERE for more information on this insect and details of its first discovery at Blue Jay Barrens.

Blogger is not letting me upload videos today, so I've included three links to videos showing typical hunting behavior for this species.  Click HERE 1 and HERE 2 and HERE 3 to view the videos.  For best viewing, select the full screen option on YouTube.


  1. Never heard of it before. Glad it doesn't bite!

    1. Hi, Stew. Unfortunately, or fortunately, depending upon your point of view, the Elephant Mosquito does not range far enough north to make a presence in your area.

  2. ...very cool, Steve. I've never seen one (but I've never looked for one either--I didn't know they existed). I wonder if they ever venture just north of Cincinnati to Mason?

    1. Hi, Kelly. The range map shows this species going as far north as northern Warren County, so it could show up in Mason. My two finds were both in a tub that I intentionally set out to receive mosquito eggs. Laying out the welcome mat for mosquitoes is probably a discouraged activity in most urban areas.