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Mosquito of the Month: Toxorhynchites rutilus - the Elephant Mosquito

Posted by The VDCI Team on Oct 13, 2016 12:28:42 PM

Written By Michael “Doc” Weissmann, Ph.D., Chief Entomologist

“Massive” and “giant” are not terms most of our partners want to hear associated with insects, especially mosquitoes, in their community. Toxorhynchites rutilus is the largest mosquito in the USA. An adult female can have a wing span of nearly ½ inch, and if it sat on a quarter, the tips of their long legs could dangle off the edges. Yeah, I’d call that massive.

Toxorhynchites_rutilus_septentrionalis_DallasTX_JasonWilliams250.jpgBut fear not – these giant, day-flying mosquitoes do not need a blood meal to produce eggs, so they do not bite. Due to their lack of interest in taking a nibble, they are only caught in certain kinds of traps associated with mosquito surveillance, and cause little concern in the field of mosquito control. Both adult males and females feed exclusively on sugary substances – primarily flower nectar but also plant sap, honeydew, and juices from rotting fruit. They are sometimes called “elephant mosquitoes” due to their long, trunk-like proboscis that curves downward and is pointed at the tip to assist in sucking nectar from deep flowers. Since they don’t bite, they also don’t transmit any vector-borne diseases. Whew!

Toxorhynchites rutilus is also one of the most colorful mosquitoes in the USA. The body is covered with shiny, metallic, dark-blue scales, with patches of iridescent silvery-white, purple, and green scales ornamenting the sides of the thorax and abdomen. They are stunning, beautiful, and just down-right gorgeous.

VDCI_Toxorhynchites_rutilus_Dallas_Texas_Web.jpgThe species is not common, but widely distributed throughout the southeastern USA, as far north as the Great Lakes, and west into Kansas, Oklahoma, and Texas. In warmer southern states, adults can be found nearly year-round, while in the north they overwinter as larvae.

Adult females lay bright-white eggs directly on the water surface in small containers, especially tree holes, pitcher plants, rock pools, and bromeliads, but additional larval habitats can also include man-made containers such as tires, bird baths, and flower pots.

The larvae are also much larger than other mosquito larvae, and quite colorful – a deep reddish color on the back, and greyish on the underside.

Most mosquito larvae filter bacteria and algae from water for food, but not these giants. Also known as “mosquito-eaters” or “cannibal mosquitoes,” they are predators on other mosquitoes and occasionally on each other. Their mandibles are unusually stout with comb-like extensions used for grasping prey. Because the larvae feed on other mosquito larvae, some attempts have been made to introduce various species of Toxorhynchites as biological control agents, but with only limited success.

Big, beautiful, and beneficial – these harmless mosquitoes should be regarded as an exception for anyone who believes that the only good mosquito is a dead mosquito.

 

VDCI is committed to public education and spreading awareness throughout the U.S. about the dangers of mosquito-borne diseases and their preventability, with the overarching goal of reducing illness and fatality statistics. Our dedicated and experienced staff works tirelessly to prevent the spread of mosquito-borne diseases in all of the contracts we service. If you would like more information about any aspect of an Integrated Mosquito Management (IMM) Plan, including mosquito surveillance, disease testing, or adult control, please contact Vector Disease Control International (VDCI) and we will help you get started immediately.

Michael_Doc_WeissmanPhD.jpgMichael “Doc” Weissmann is the Chief Entomologist at Colorado Mosquito Control, a VDCI company. He has been identifying mosquitoes since the mid-1980s, and has been in charge of the Surveillance Laboratory at CMC since 2003. Doc received his B.A. and M.A. in Biology from the University of Colorado, and his Ph.D. in Entomology from Colorado State University. He can be reached through the VDCI website or by calling 800.413.4445.



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Since 1992, Vector Disease Control International (VDCI) has taken pride in providing municipalities, mosquito abatement districts, military bases, industrial sites, planned communities, homeowners associations, and golf courses with the tools they need to run effective integrated tick and mosquito management. We are determined to protect the public health of the communities in which we operate. Our tick and mosquito management professionals have over 100 years of combined experience in the field of public health, specifically vector disease control. We strive to provide the most effective and scientifically sound mosquito surveillance and control programs possible based on an Integrated Mosquito Management approach recommended by the American Mosquito Control Association (AMCA) and Centers for Disease Control and Prevention (CDC). VDCI is the only company in the country that can manage all aspects of an integrated tick and mosquito management program, from surveillance to disease testing to mosquito aerial application in emergency response situations.

Topics: Mosquito of the Month Series