The Zika virus and Chester County

by Nathaniel Smith, The Times of Chester County, 9/1/16

Getting rid of standing water is more effective than spraying

News has come around lately that “Pennsylvania Is Now One Of The Top States With Zika Virus ” (Phoenixville Patch, 8/23/16). Currently PA ranks 5th in the number of diagnosed Zika cases. Of course, no one knows how many undiagnosed cases there are anywhere.

Quick quiz: how is Zika spread? If you answered “by mosquitoes,” you’re only half right. It’s our fault too.

It’s important to focus on this note in the article: “All of the cases were travel-related, according to the Centers for Disease Control and Prevention.”

That means no human has acquired Zika from a mosquito in PA. Although the prime mosquito host for Zika, aedes aegypti, does exist in Pennsylvania, it doesn’t do well this far north (yet).

The fact is that Zika is spread not only by mosquitoes but also by people, whether through sexual contact (CDC offers explicit advice on this aspect) or from carrying the virus (usually without symptoms) and being bitten by a mosquito that in turn bites someone else, who thus acquires the disease. The aedes albopictus mosquito, often called “Asian tiger,” has become very numerous in PA but fortunately does not seem to transmit Zika very well (yet).

Spraying pesticides is a limited, short-term fix that leaves many adult mosquitoes alive and does not affect eggs and larvae but harms many forms of life and can lead to acquired immunity. Mosquitoes breed over 500 times faster than people, so they will become immune to whatever we do against them much faster than we can evolve to resist them. Mosquitoes in Puerto Rico and Florida are already becoming resistant to permethrin, the standard anti-mosquito pesticide.

This is all not good news, except that in PA we do have some time to get ready for present and future mosquito-borne diseases….

read more at The Times of Chester County

Mosquito traps made from old tires are 7 times more effective than standard traps

by Melissa Breyer, treehugger, April 8, 2016

A new study found this cheap, easy system significantly reduced virus-carrying Aedes mosquitoes in Guatemala.

Called an ovillanta, a simple mosquito trap fashioned from old tires spells doom for mosquito eggs. So effective is the cheap eco-friendly system that during a 10-month study in Guatemala, the team collected and destroyed over 18,100 Aedes mosquito eggs per month, almost seven times the eggs collected compared to standard traps. Anecdotally, the researchers note that there were no new reports of dengue during the time in the area, normally during that timeframe the community would have reported up to three dozen cases.

The Aedes genus of mosquitoes is primarily responsible for transmitting a host of vexing viruses, including Zika, dengue, chikungunya, and yellow fever. Aedes is notoriously tough to control, according to the World Health Organization. Pesticide-resistance, lack of resources, and a boost in mosquito-friendly environments have hindered traditional methods of controlling the pest’s quick spread.

Created in collaboration by researchers from Canada and Mexico, the ovillanta is made of two 20-inch sections of old car tire secured together in the form of a mouth, with a fluid release valve at the bottom. A milky mosquito-luring non-toxic solution is poured in the bottom – the solution includes a mosquito pheromone that tells female mosquitoes that it’s a safe place to lay eggs. The mosquitoes enter, lay eggs on a paper or wooden strip that is floating in the “pond” … twice a week the little egg raft is removed, the eggs destroyed, and the solution drained and filtered before being reused in the trap again….

ovillanta old tire mosquito trap

read more at treehugger

Larviciding with Bti

A larvicide (or larvacide) kills larvae.

In a rare too-good-to-be-true moment, the biological agent Bti prevents mosquito larvae from maturing. It’s made from bacteria called Bacillus thuringiensis israelensis, which affects no other forms of life except two other nuisance insects (black flies and midges). It is organic and totally non-toxic.

You can use mosquito dunks in any standing water that you can’t dump out regularly: a small pond or stagnant stretch of stream in your yard, or a built-in plant soaking area that no longer drains, etc.

For a small surface area, just break up the dunks in pieces. In any case, reapply every month or so to be sure the Bti is still active.

Dunks usually come in packs of 6 dunks. If you buy more than one at a time at ACE hardware store in East Bradford (720 W Strasburg Rd., just west of West Chester borough, after Daily Local News), ask for a discount.

Just to remind you, we don’t promote the use of pesticide sprays and SPRAYS HAVE NO EFFECT ON LARVAE (or on pupae, the cocoon-like form that larvae go through before emerging as adults).

For detailed information on Bti, see “Best Natural Mosquito Control: Bti” at mosquitoreviews.

Mosquito dunks

The Shaker Heights plan

Shaker Heights, Ohio, initiated a successful mosquito control program in 2002. They outlined a plan with 6 levels of response, with the highest being the type of health crisis that suggests that pesticide spraying is necessary. Their Health Director, Sandi Hurley, reported to Don’tsprayme in June of 2016 that, during the 14 years that these guidelines have been in place, Shaker Heights has had no serious cases of West Nile virus and no health emergency that required spraying.

That community, which is about 6 square miles with a population of 28,000 people, works together cooperatively to keep Shaker Heights safe by reducing standing water and mosquitoes and by not spraying pesticides. One of their chief lines of defense is larviciding all storm drains. West Chester, working with the County, has been larviciding storm drains on a selective basis in 2016.

To download their 6-step plan, of which we are preparing a modified version to recommend for West Chester, click here: Shaker Heights WNV Response Plan

Mosquitoes, meet your maker. A DIY trap kills thousands of the biting bugs

[Please let us know if you try this non-toxic mosquito elimination method… and give thanks we don’t have the biting population New Orleans does!] By Susan Langenhennig, The Times-Picayune, May 27, 2014

If you’re waging war on mosquitoes, don’t waste your money on a bug zapper. They aren’t much of a solution. You’re more likely to catch moths than mosquitoes in the buzzing devices, and, as the New Orleans Mosquito, Termite and Rodent Control Board says, “bug zappers do more harm than good.”

If you want a DIY weapon for your fight against the bite, Dan Rojas of has an easy, inexpensive trap that’s both effective (it will kill thousands of mosquitoes in just 24 hours) and gratifying (you take the battle to the bugs without lifting a bottle of DEET).

In a video posted on, Rojas uses magnets to attach a mesh screen to the back of a standard-issue box fan, the kind you can find in any big-box home improvement store….

read more and see video at The Times-Picayune

Pesticide Environmental Stewardship

We applaud the Chester County Health Department and US Environmental Protection Agency for their commitment to reducing pesticide risks:

“The Chester County Health Department is a member of the Environmental Protection Agency’s Pesticide Environmental Stewardship Program. This program requires participants to affirm that environmental stewardship is an integral part of their integrated pest management (IPM) practice, use current, comprehensive information regarding the life cycle of mosquitoes within their IPM program, educate the community on the benefits of IPM, and demonstrate a commitment to pesticide risk reduction activities.”

(Wording from the County’s 5/19/16 release under the heading “Make your home a Mosquito-FREE zone” at CHESTER COUNTY HEALTH DEPARTMENT).

No breeding mosquitoes… it’s a matter of public health!

from the Chester County Health Department Rules and Regulations:

502.5.1.1. No person shall maintain or permit to be maintained any pond, privy vault, cesspool, well, cistern, rain barrel, individual sewage system, community sewage system, or other receptacle or system containing water, unless such receptacle or system is constructed or maintained in a manner to prevent the breeding of mosquitoes, flies, or vectors of disease.

What can I do to reduce the mosquito population?

Here is the enemy: larvae

But those are mosquito larvae, which don’t bite.

Right, but once larvae hatch, it is really too late for that batch. One female mosquito, with an occasional protein infusion from blood, lays 100+ eggs. The eggs hatch into larvae (as pictured), which fly away as adults in a few days.

Can’t we just spray and kill all the mosquitoes?

Air-borne insecticides, a temporary fix, may kill 80% of adult mosquitoes in the vicinity, but do not affect eggs, larvae, or pupae (the larvae who have already moved to a cocoon-like phase). Within a few days, the population is restored. Besides, many species can fly a mile or more. And even worse, the more we spray, the more likely mosquitoes are to become resistant to the insecticides we use.

So what do we do?

We must eliminate stagnant water! It sounds easy but requires imagination. Empty out birdbaths, pails of water, saucers under plants, and whatever else can hold water. And look overhead: be sure your house eaves drain. Spill out ALL standing water every 3-5 days to be safe.

How about ponds and streams?

A biological agent called Bti, widely available, prevents larvae from growing into adults. If the water is running, no problem. Swimming pools usually have enough chlorine to kill larvae.

Where can I get more information?

West Chester Borough has a new program and web page for residents to help their neighbors eliminate mosquito breeding. See here.

The County has two relevant pages, one on avoiding mosquito-borne diseases generally and one more specifically West Nile Virus. Both stress how to keep mosquitoes from breeding on our property. In fact, the County health regulations require us to avoid breeding mosquitoes.

See also excellent advice from the West Baton Rouge Parish Council Mosquito Abatement program, including video showing where mosquito larvae flourish and what they look like.

And talk to your neighbors, especially any who may be circulating information on mosquito control.

Chester County Health Department offers advice on prevention of mosquito-borne diseases

Press release from CHESTER COUNTY HEALTH DEPARTMENT, May 19, 2016

Make you and your home a bite-free zone

West Chester, PA – Now that the weather is warming up, the Chester County Health Department encourages county residents to “Make you and your home a bite-free zone”, reducing the risk of mosquito-borne diseases like West Nile virus and Zika virus.

Because mosquito-borne diseases are spread through the bite of an infected mosquito, residents can reduce their risk by using insect repellent and other personal protection and getting rid of standing water on their property…

download the full release under the heading “Make your home a Mosquito-FREE zone” at CHESTER COUNTY HEALTH DEPARTMENT