‘Ghouls on wings’ bug Yellow Springs
- Published: August 6, 2015
“How you sail like a heron, or a dull clot of air,
Yet what an aura surrounds you;
Your evil little aura, prowling, and casting a numbness on my mind.
That is your trick, your bit of filthy magic:
Invisibility, and the anæsthetic power
To deaden my attention in your direction.”
—Excerpted from “The Mosquito”
by D.H. Lawrence
As local artist Deborah Chlebek was painting on the bike path recently, she took a moment to acknowledge her gratitude for the breeze keeping the mosquitoes at bay. Her home is currently besieged by mosquitoes, and Ellis Pond, one of her preferred outdoor painting spots, is host to a uncommonly large number of biting insects as well. Chlebek is correct in her lament that mosquitoes are worse this year than usual.
Their abundance in Yellow Springs is not the punchline to a cruel celestial joke but the result of an unusually wet June and July. The amount of rain this summer has provided many opportunities for mosquitoes to breed, said Vickie Hennessy of the Green Environmental Coalition, or GEC. The pools of still water that form in places like tree holes, gutters, and corrugated roofs are perfect mosquito breeding grounds. Mosquitoes can go from egg to full-grown adult in about a week, secretly flourishing in these places before anyone is the wiser.
Removing these sources of standing water is a simple yet important step in mosquito control, according to Hennessy. The step curtails population growth, cuts down on summertime bites and is also a safety precaution because mosquitoes can be vectors for potentially serious disease. And a proactive elimination of breeding sites now cuts down on the need for adult-killing pesticide later, said Village manager Patti Bates.
For the past two years, local mosquito control efforts involved monitoring the mosquito populations in different areas of the village. GEC worked with Antioch biology professor Savitha Krishna and her students to conduct weekly larvae checks and to map the village’s worst breeding grounds. The work was paid for with funds from Village government, which used the group’s findings to determine what control measures it should take. But the funding wasn’t renewed this year and responsibility for monitoring mosquito populations has reverted back to Village government. The Village in turn contracts with the health department for larger-scale applications of pesticide, and if necessary to test populations for disease.
But Village government has not done any testing or spraying this year because the mosquitoes are currently more an annoyance than a health risk, said Bates, who has not received any complaints about mosquitoes so far this year, and complaints are usually what prompts an investigation or chemical response. There have been no cases of West Nile Virus in humans or animals in Ohio at all this year, nor have there been any reported cases of encephalitis. According to the Ohio Arbovirus Surveillance Update issued July 10, only 11 of the 3,171 mosquitoes tested in the state carried West Nile Virus, and they were found in central and northeastern Ohio.
Confronting the menace
When mosquitoes are a threat, however, the health department employs a three phase “integrated pest management” program to combat it. The first line of defense is minimizing the opportunities to breed. The second and third steps involve going on the offensive.
“We work with homeowners to get rid of all standing water,” said Marc Isaacson, project manager for special services for the environmental health division of the health department.
Troughs and tires full of water are perfect breeding grounds for mosquito larvae, as are sites not normally recognized as such, like boat covers, flowerpots, and the errant plastic bucket. Homeowners can undertake other preventive measures such as frequently changing birdbath water, stocking ponds with fish that eat mosquito larvae, and filling grassy areas that tend to hold water with dirt. The Ohio Department of Health also recommends repairing leaky faucets and pipes to reduce the number of places where water collects, and keeping vegetation trimmed because mosquitoes use shady areas for resting places.
If pools of water can’t be emptied, larvacide may be employed to kill mosquitoes during their early stages. Bacillus thuringiensis var. israelensis, or Bti, is a bacterial strain dumped into mosquito nurseries that kills larvae when ingested. (Homeowners can buy Mosquito Dunks at any garden store, which are basically Bti tablets for treating ponds and other sources of backyard water.) The health department and GEC agree that larvacides are less hazardous to the environment and more effective than the next step, pesticide.
The last resort is pesticide designed to kill adult mosquitoes. To take this step, there has to be evidence of “nuisance conditions” — proliferation beyond what might normally be expected — or evidence of disease. Greene County uses a pesticide called Anvil 2+2, a fine mist sprayed wholesale over mosquito habitat. The noxious fog hangs in the air for 20–25 minutes and one drop is sufficient to kill a mosquito. According to Isaacson, the pesticide is safe for humans and animals because the droplets are too small to affect large creatures.
The village and pesticide
However, villagers don’t need to worry that health department officials will show up in their yard bearing pesticide spray anytime soon.
“If spraying is necessary,” said Isaacson, “all options are discussed with the Village Council and manager to determine the most advantageous way to manage areas where there is a concern.” Yellow Springs has found that the most advantageous way is to stop mosquitoes before they start, and to keep pesticide use to a minimum.
Part of the Village’s agreement with the health department allows local officials to determine how spraying will be carried out in the village. Yellow Springs residents are able to opt out of having their properties sprayed by requesting that the county’s pesticide trucks skip their properties, said Debbie Leopold, Director of Environmental Health Services for the health district. No significant updates to the Village’s spraying policy have been made recently because spraying hasn’t been necessary in the last few years.
The current policy stems from the discovery of mosquitoes carrying West Nile virus near Southgate Avenue in 2012. While the virus only affects about 20 percent of those who contract it, in serious cases it can cause inflammation of the spinal cord and brain, coma and death. The virus prompted a response from the county that included a campaign of airborne pesticide.
But the use of pesticide drew complaints from residents, who had concerns about its effects on health and the environment and its perceived inefficacy overall. According to GEC, Anvil 2+2 is an “indiscriminant pesticide that kills beneficial insects” and that has been linked to cancer and asthma. Moreover, it only works if the pesticide directly hits a mosquito, and a Cornell University study shows that the percentage of pesticide that actually reaches its target hovers around .0001 percent.
“It is the most visible method, and the least effective,” said Isaacson.
Of course mosquitoes, like any creature, play an important role in the ecosystem. Their principal benefit seems to be the role they serve as food for larger creatures. Their larvae are nutrient-packed food for fish, and adults are food for creatures like bats, owls, and other insects. Some element of tolerance for their presence is permitted knowing other creatures are being fed, but studies have shown that the amount of mosquitoes consumed by other creatures doesn’t actually make a difference to the overall mosquito population.
“I’m not sure if there is anything a mosquito is good for,” Isaacson said. “As a general rule, they are considered a nuisance and not particularly helpful.”