After the deluge, come the mosquitoes
It is on, mosquitoes. This sopping spring guarantees Houstonians will have to be more vigilant against the pests than ever.
The mosquito kills about 1 million humans a year, chiefly from malaria, making it by far the deadliest life form on the planet, reports the World Health Organization.
The city has already logged its first case of West Nile virus this year, even though the season usually peaks in August.
Houstonians have a couple of weeks to gear up for the mosquito onslaught, said Joe Conlon, an entomologist and technical adviser with the American Mosquito Control Association.
The floodwaters from the recent heavy rains washed many of the existing larvae away, but the puddles remaining give the next generation of troublemakers a good nursery. “Then the problems will start in spades,” Conlon said.
Dry weather over the past few years has suppressed insect numbers, but that’s all over now, said Sonja Swiger, an entomologist with the Texas A&M AgriLife Extension Service in Stephenville.
“The flood put a twist on things,” she said. “It’s going to be overwhelming in a couple of weeks. Lots of rain activates mosquitoes,” she said.
Even though one batch of larvae is gone, more will follow. “As soon as the rain quits, it’s all going to let loose,” she said.
Rogues’ gallery
It would be hard to find a creature as ecologically useless and universally despised as the mosquito. What good are they, after all? Not much, Conlon said. “They’re not the sole food source for anything on the planet,” he said. If they disappeared tomorrow Mother Nature would merely hiccup.
“They’re the ultimate survivor,” he said, and have been for 175 million years, making do at 14,000 feet on mountains and 5,000 feet down in mine shafts. They survived the dinosaurs.
Only the female mosquito bites — or, rather, plunges her proboscis into skin — because she needs a blood meal to produce eggs. When she does, she can introduce a disease virus or parasite into a human or animal.
The Houston area is home to a rogues’ gallery of mosquitoes, Conlon said. Black-and-white Aedes aegypti (the yellow fever mosquito) and Aedes albopictus (the Asian tiger mosquito) are both “para-domesticated,” meaning they’re dependent on humans for life.
They rarely venture more than 300 to 500 feet from their place of origin, and they like to bite during the day. Count on them to spread diseases such as Dengue fever and chikungunya, though fortunately not in this area, yet.
Aedes likes to hang around houses and breed in any standing water — even in a soda-bottle cap. If you see Aedes at your house, you didn’t get rid of all your standing water.
Toward the Gulf Coast, expect to encounter Aedes taeniorhynchus, the salt-marsh mosquito, an aggressive biter and distance flier who doesn’t care what time it is at mealtime. “Galveston, they’re horrible there,” Conlon said.
Then there’s Culex, a tan dawn-and-dusk biter that can spread West Nile virus, St. Louis encephalitis, Japanese encephalitis and dog heartworm.
In the case of West Nile, the insects pick up the virus from infected birds, said Dr. Robert Tesh, a physician and professor of pathology at the University of Texas Medical Branch in Galveston. They then transport it to other birds, mammals or humans. (This is why the presence of dead birds is an indicator of West Nile.)
Culex prefers polluted water, so urban culverts and drains make excellent breeding grounds.
West Nile can be serious, especially in the elderly and those with weakened immune systems, Tesh said. It works its way into the nervous system, causing fever and other symptoms that can leave the patient weakened for months — or, in rare cases, dead. “In younger people it’s not that big a threat,” he said. It can cause a flu-like illness or have no symptoms at all. There’s no cure.
Garlic won’t help
Why do some people seem to attract mosquito bites while others don’t?
Genetics, Conlon said. “Some people are not intrinsically attractive and give off odors repellent to mosquitoes,” he said. Others, especially with fairer skin, seem desirable. Nothing you can eat will fend them off, not even garlic.
Gardening with plants such as citronella grass also doesn’t do the trick because the concentration of the oil mosquitoes hate is too weak. Nor is Conlon a fan of all-natural essential oil concoctions, saying they are unproven and risky in light of the dangers from diseases. He recommends an Environmental Protection Agency-registered repellent. “It could be a matter of life and death, literally,” he said.
In any case, Tesh said, we’re not going to win this fight. “It’s not a matter of winning. We’re all just surviving,” he said. “I’m afraid they’re here to stay.”