Wet spring could mean more mosquitoes
A wet spring resulting in more water in Carson City’s traditional mosquito breeding areas means extra vigilance on the part of the city’s Division of Environmental Health.
“There is always the potential for more breeding activity with more standing water, but as we warm up, the smaller areas may dry up,” said Dustin Boothe, supervisor of the division.
Boothe said Brendan Schnieder, a new environmental health specialist hired for the division at the end of March to replace an outgoing specialist, has already been out in the field dipping water and searching for signs of larvae.
“We’ve had a few citizens call, but there could be other flying insects hatching right now that aren’t necessarily mosquitoes,” Boothe said.
With the colder temperatures this week, larvae don’t necessarily die.
“It takes them longer to develop from egg to mosquito in cold water. If the water freezes, that could get rid of the larvae, but they can still dive down. If they’re in the pupa stage, though, they’ll drown, because they need to breathe from the surface of the water,” Boothe said.
Generally, in warm weather, the life cycle from egg to adult is three to seven days, but in cold water, the cycle slows down and can take anywhere from 10-15 days.
Aerial applications using a helicopter will be conducted next month, but because of budget constraints, there will be only one application until the start of the new fiscal year on July 1. Washoe County is starting today.
The application is an insect growth regulator that will prevent the emergence of biting adult mosquitos.
Carson City’s vector control will focus on traditional areas where mosquitoes can become a problem such as the river corridor, Silver Saddle Ranch, Anderson Ranch and Empire Golf Course.
Boothe’s division conducts regular surveillance of known mosquito-breeding sources all over town.
He said there are two mosquito types to watch out for in our area.
“The permanent-water mosquitoes are the ones biting at dusk and dawn,” he said, “while the flood-water mosquitoes are more aggressive and bite at all hours.”
Carson City uses a number of methods in its vector control program:
• An insect growth regulator called Altosid only affects mosquito larvae, preventing their development. It is effective for about 120 days.
• Agnique is used less frequently, but for large infestations. It destroys the surface tension of water so mosquitoes drown, but so do other insects.
• Fogging is used only when necessary, but it kills all flying insects.
Boothe said the city prefers the more ecofriendly approach, but occasionally, stronger methods are called for to protect public health.
Carson City works with the Department of Agriculture as well as Washoe County’s health division to test for mosquito-borne viruses. The three they watch for are West Nile virus, the St. Louis Encephalitis virus and the Western equine encephalitis virus.
Scott Monsen, coordinator for Washoe County’s Vector-Borne Diseases Prevention Program said that “this has been a record year for precipitation in the Sierra. Generally, the more water there is, the larger the mosquito hatch. That’s why it is so important for people to protect themselves with repellent whenever they are outside this summer.”
• Clear the yard area of any free-standing water that may become a mosquito breeding ground.
• Wear long sleeves and long pants in mosquito prone areas.
• Use mosquito repellent, such as DEET, and follow label precautions.
• Repair any window screens that could provide entry for mosquitoes.
• Vaccinate horses for Western Equine Encephalitis and West Nile Virus.