Mechanical control is a means by which adult mosquitoes are physically prevented from coming in contact with people. This is also called exclusion. Maintaining window screens by keeping them in place and patching holes that may have developed over time will help prevent mosquitoes from entering dwelling and biting inhabitants, especially in the evening when they often make their presence known as people and pets sleep.
For those that live in houses with screened-in porches, windows and door screens, such an insect-excluding device is taken for granted. Yet, less than 50 miles away in what was the focal point of West Nile virus in 1999, you could drive around the area a year later and see that the majority of windows in apartment buildings were not screened. One of the ironies of the 1999 outbreaks was the case of the man who would wake up in the middle of the night and go out on his back porch to take in the night air. Unfortunately, his was not a screened in porch. It was, as Yogi Berra said, “Deja vu all over again,” for the Egyptians who lived in mosquito-plagued areas of the Nile delta around 450 BCE built towers in which to live so as to escape the pestiferous insects. The residents of Queens felt that living in the upper stories was adequate protection. One wonders if the sales of window screens in New York City skyrocketed because of West Nile virus. The Egyptians, as well as the ancient Greeks, also reportedly used fine-mesh nets to protect themselves.
Before the discoveries of Manson, Ross, Finlay and Reed, mosquito netting had proved invaluable to David Livingstone who slept under a “mosquito curtain” during his travels in sub-Saharan Africa- known then as “the White man’s grave” because of malaria and yellow fever and today, an area where a child dies of malaria every 30 seconds. A search of the internet for information on mosquito netting reveals the name Jane Delano, a nurse, who, before the relation of mosquitoes to yellow fever was known, wanted the use of mosquito netting to prevent the spread of this dreaded disease.
Mosquito netting even served as a subject for the great American painter John Singer Sargent who painted to portraits of ladies reclining with mosquito nets to protect them. An excellent new book, The Fever Trail: In Search of the Cure for Malaria by Mark Honingsbaum, has a photo of a British malariologist with a head net on the cover, and those who follow the trail of mosquitoes and malaria prevention are aware of the current efforts to introduce treated bed nets as a means of controlling malaria. On a personal note, I remember sleeping under mosquito netting in Tsingtao, China, in the summer of 1946 because two US servicemen had died of Japanese B encephalitis.
The development of what many consider an essential part of a house can be dated quite precisely. In 1874, Chester Wickwire (and, yes that was his name) produced 150 square feet of hardware cloth for use in excluding flies. In 1876, he sold his hardware store to devote his energies to producing bronze wire screening, and by the mid 1880s he was producing some 30,000 square feet annually. The Wickwires produced the screening that was used so effectively in Gorgas’ plans for preventing mosquito-borne disease during construction of the Panama Canal. Later, in the 1920s, Wickwire Brothers produced some 25% of the world’s wire cloth.
The number of cases of malaria, which was endemic in the South until the 1940s was greatly reduced by the installation and routine repair of screens by local departments of health with the support from the Rockefeller Foundation.
Those of us who have spent our time in mosquito control work tend to take screens for granted as they have been such a natural part of our lives.
We should remember that exclusion is a fundamental part of an integrated pest management program. Our efforts have been directed at protecting the citizens we serve by reducing mosquito populations, but we should not forget that exclusion is a valid principle, particularly when the elements conspire to create mosquito populations that get out of hand.
New Jersey Mosquito Control Association Newsletter
Vol. XIV September 2002
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