EDINBURG — Mosquitoes: they’re more than just an itchy nuisance; they’re a potential risk to public health and safety. And in the aftermath of last Monday’s heavy rains, the pesky critters are out in force, causing local officials to scramble to deal with the issue.
Eddie Olivarez, chief administrative officer for the Hidalgo County Office of Health and Human Services, put the current numbers of mosquitoes in perspective with one vivid example. “Some of our team went out to trap on Friday of last week … and within a 12-hour period, there was 4,000 mosquitoes caught in one trap,” Olivarez said.
“ We usually average only 40-50 on a normal day. But, 4,000, that’s a lot.”
The Delta area — which bore the brunt of last Monday’s storms — is now feeling the prick from the swarms of hungry insects which have arisen since.
“ Mosquitoes are tough,” Elsa City Manager Juan Jose Ybarra said in a phone interview Wednesday afternoon. “We’ve been spraying after the rain, throwing mosquito dunks,” he said, referring to chemical tablets — known as larvicide — that target mosquitoes in their larval stage of development.
Next door, Edcouch city officials say they began their mosquito control efforts the day after the rain. “Larviciding we started as of the second day when we brought in the movacs and we were pumping water out,” Edcouch City Manager Victor Hugo de la Cruz said. “At that point, they were larviciding and they were dumping the tablets.”
And just a few days ago, Edcouch added fumigation to their arsenal, as well.
In Weslaco, officials are also using a two-pronged attack of applying larvicide to areas of standing water while spraying insecticide across the city.
“ We’re spraying every day,” Weslaco City Manager Mike Perez said, adding that vector control personnel target different areas of the city to spray each night in order to maximize the effectiveness of the mosquito control efforts.
Olivarez explained why residents won’t be seeing a mosquito truck in their neighborhoods every single night. “Believe it or not, just like humans get a resistance to antibiotics, mosquitoes and mosquito larva get a resistance to the poison,” Olivarez said.
And officials have the evidence to back that up.
After last June’s flooding, the University of Texas Rio Grande Valley and the Texas Department of Health and Human Services began a year-long study in counties that border the Rio Grande from El Paso to Brownsville with the intention of analyzing the effectiveness of various insecticides on mosquitoes. They discovered the insects have become immune to at least one popular insecticide, Olivarez said.
“ We are discouraging the use of that particular type of (insecticide) for this year,” Olivarez said.
Earlier this week, county officials met with leaders from the various communities affected by last week’s rain in order to combine their vector control efforts. It’s something that has been made possible thanks to the county’s recent disaster declaration. Otherwise, Olivarez said, each individual municipality would be responsible for their own mosquito control efforts.
In Elsa, that cooperative approach is welcome news. Ybarra said the city’s efforts at combating the insects have been hampered by the proliferation of mosquitoes outside city limits.
“ Some of the areas to the north still have standing water. Some areas southeast still have standing water — not in Elsa, but in the county area,” Ybarra said.
In Weslaco, where officials have noticed a similar trend, they hope widening the spraying perimeter will help mitigate the issue. “We’re spraying a little bit outside the city because mosquitoes don’t know, ‘Oh, there’s the city limits of Weslaco, we can’t cross that line,’” Perez said.
The city manager added that crews would be ramping up their efforts overnight Wednesday since a number of people are expected to be outdoors today celebrating Independence Day.
Though the sight of a fumigation truck slowly making its rounds through neighborhoods is a reassuring one, Olivarez explained spraying is the least effective method of controlling the bloodsuckers.
Using larvicide to kill them before they can mature “by far, is the most effective way to deal with mosquito control,” Olivarez said.
After that? The best defense is a good offense spearheaded by property owners themselves. “The individual resident plays a huge role in this,” Olivarez said.
He urged residents to get rid of standing water, old tires, trash and debris. Too, he said residents should trim their grass and make sure any window or door screens are in good condition.
Of the 26 species of mosquito that exist in the Rio Grande Valley, only three have the potential to spread disease. “That’s the culex mosquito, which is very abundant in our area, the Aedes aegypti and the Aedes albopictus ,” Olivarez said.
“ Culex can carry West Nile fever, (and) malaria, which is not common here. The Aedes aegypti and the Aedes albopictus , they’re with Zika, dengue and chikungunya — if they’re infected,” he said, with a strong emphasis on the word “if.”
However, in two years of trapping and testing mosquitoes, researchers have only encountered “one situation where we had a West Nile case,” Olivarez said.
Olivarez also had a note of caution horse owners. “Horses, especially with the culex mosquito, can obtain West Nile virus and it can be deadly for a horse,” he said, adding that a West Nile vaccine is available for horses and donkeys.