Mosquito Assassin Bugs Show Promise in Texas

Mosquito Assassin Bugs Show Promise in Texas

June 10, 2019

Probably the last thing in the world that residents of the Houston, Texas, area would like are more bugs.

Harris County already has one of the worst mosquito problems in the nation. The warm, humid climate is a prime breeding ground for the dangerous insects, and it’s been made worse recently by weather that’s even warmer and wetter than usual.

The county, according to an article in the Houston Chronicle, is fighting the mosquito problem by breeding and releasing “mosquito assassins” in the area. In other words, more bugs. However, these insects kill mosquitoes that bite humans and spread disease. It’s part of the county’s Biological Control Initiative to limit the pest population.

In addition to the insects being released into the wild, the mosquito assassins also have been released inside the Houston Museum of Natural Sciences’ Cockrell Butterfly Center. Researchers there are examining the mosquito assassins’ effect on mosquitoes and other organisms.

The once-common mosquito assassins can still be found, but not in heavily urban areas. They attack the Asian Tiger, Southern House and Yellow Fever mosquitoes, three types known for spreading disease.

The best news: he mosquito assassins, a.k.a. Toxorhynchites rutilus, are not interested in humans.

There has never been a better time for this.

Mosquitoes lay their eggs in standing water, so more rain equals more mosquitoes. Rain means puddles and standing water in places like tires, birdbaths, dog bowls, baby swimming pools or anything else in someone’s backyard that would collect rain water.

Mosquitoes also love warm weather. Research has shown the warmer it gets, the more efficiently mosquitoes transmit West Nile, Zika and other viruses. In addition to transmitting disease to people, mosquitoes bite and transmit disease to animals, including heartworm to dogs.

Enter mosquito assassins.

As larvae, the mosquito assassins eat other organisms within reach. When they’re adults, they don’t need the protein that mosquitoes get from blood. The assassins lay eggs in rainwater-filled vessels where mosquito larvae are likely to be found. When the assassins hatch, they feed on aquatic insects, including mosquito larvae. Mosquito assassins can be spotted by their size (they are much larger than the average pest mosquito) and their eye-catching color, a metallic-looking blue and gold.

According to a report at, studies in Louisiana showed that the release of mosquito assassins, followed by a small insecticide application, reduced the target pest population by 98%. Using insecticide alone only led to a 29% reduction.

The mosquito assassins are not available for purchase, as they must be raised by insect experts. Because of this, and the difficulty in producing enough mosquito assassins to significantly cut the number of mosquitoes, this approach is rarely used.

However, according to an article at Entomology Today, this latest case in the Houston area shows promise because researchers have produced numbers of mosquito assassins more efficiently by raising them individually instead of in batches. When raised together in the past, the mosquito assassins ate each other. Raising them individually is producing better numbers with the goal of cutting back on flying insect nuisances.

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