West Nile virus

Mosquitoes that can carry West Nile virus breed in standing water.


Two Pennsylvanians, one from Lancaster County and the other from Lebanon County, have died after contracting West Nile virus. Through Tuesday, there have been 40 statewide human cases this year of the virus, which is spread by infected mosquitoes and can also be passed on to birds and animals. Three of those human cases have been in Lancaster County. During the summer, mosquitoes infected with the virus were found at 72 locations throughout the county. The threat of the virus and its spread by mosquitoes will remain until the first hard freeze.

We’ve officially moved from summer to autumn, but now is not the time to drop our collective guard for the West Nile virus season in south-central Pennsylvania.

Harlan H. Hoover, 81, of Gordonville, died Sept. 17 at Lancaster General Hospital “after contracting West Nile virus,” according to his obituary in LNP. His is one of two deaths in the state attributed to the mosquito-borne virus.

We can’t prevent every case of West Nile virus, and, sadly, we can’t completely stop it from taking lives. But there are things we should continue doing to significantly reduce this public health threat.

It’s been extremely wet in Lancaster County during the second half of the summer and into the beginning of autumn. That water has collected in stagnant puddles, gutters, retention ponds and thousands of other potential breeding grounds for mosquitoes. All that water has keep the threat levels for mosquitoes and West Nile virus high.

Don’t take our word for it.

In a video, the Pennsylvania Department of Environmental Protection’s Matt Helwig says: “We’ve seen a high level of West Nile virus activity in the state so far this year. ... If you are being bitten by mosquitoes, it’s most likely those mosquitoes are being produced on your property. Mosquitoes do not like to travel very far. They are very weak fliers, and if they can find all the things that they need to survive on your property, that’s where they will begin and end their life cycle.”

So let’s not give mosquitoes any help with that life cycle. In fact, we can actively discourage them with some easy steps.

What to watch for

Here are things you can police on your own property, in order to eliminate potential mosquito breeding grounds:

— Yard trash, including cups and even bottle caps, which can hold enough water for mosquito larvae. A mosquito can lay 300 eggs at a time, so simply eliminating stray bottle caps can be a game-changer.

— Clogged rain gutters and downspout extensions with standing water.

— Tires.

— Covered containers, wading pools and any other items that can hold standing water for extended periods of time.

— Bird baths and animal water dishes, which should be changed regularly.

— Children’s toys in the yard capable of holding even small amounts of water.

— Trash and recycling cans.

— Flower pots, especially if there’s a saucer underneath that could hold standing water.

— Ornamental ponds without fish.

— Mower ruts.

— Wheelbarrows.

— Sewer grates on or near your property should be cleaned of debris — don’t blow grass clippings into the street — that could cause water to collect and stagnate.

— Anything else that can hold standing water.

Due diligence on the homefront in battling mosquitoes is the most effective strategy for the safety of your family and next-door neighbors. Standing water should be checked and dumped frequently; the mosquito breeding cycle is rapid.

Looking at the larger picture of residential developments, we also have concerns that not all stormwater retention ponds are properly constructed or operated to minimize mosquito breeding. All developers and municipal authorities should prioritize the management and regular review of that risk factor, especially in communities with high concentrations of elderly (and more vulnerable) residents.

Additionally, the state DEP reports that the leading producer of mosquitoes that can carry West Nile are improperly draining “urban catch basins” (stormwater grates). We are grateful that state and county officials inspect and treat more than 75,000 of these basins each year.

Helpful bacteria

State officials, including Helwig, suggest an additional line of treatment and defense. If you have stagnant water that’s going to sit for five days or more, you can use Bti, naturally occurring bacteria, to kill mosquito larvae.

It generally comes in small, disc-shaped portions, often called “mosquito dunks.” The dunks are useful in small areas of standing water, such as birdbaths or puddles that accumulate in low-lying or uneven areas of the yard. (A package of six dunks generally costs $10 or less.)

A granular form of Bti can also be purchased and is effective for larger areas, such as backyard ponds, officials say.

Bti can be purchased in many lawn and garden stores. It kills only mosquito and black fly larvae and is not harmful to people, animals, fish or plants. So, while fully eliminating standing water is always the most efficient way to reduce the mosquito population, Bti can be a useful accessory in lessening the threat of West Nile virus.

There is, knock on wood, only a month or so remaining before the first hard freeze in Lancaster County and the end of the West Nile virus threat for this season. But we should remain diligent until that time. The suggestions outlined here are not daunting or cumbersome. Building good habits now will make it that much easier to resume them next spring.

What to Read Next