The Year is 1900 and Fear of the Mosquito “Plague” hits America!

Mosquitoes became the preeminent pest in America after the 1900 discovery, by Sir Ronald Ross, that linked them to the dreaded disease, Malaria.

This was the Progressive Era, and American entomologist, Leland O. Howard, a staunch progressive, believed that problems should be identified, experts consulted, and the most effective and expedient solutions applied. And in his opinion, that meant the use of “chemicals”.

To further his cause and bolster his position, as chief of the Division of Entomology (a part of the Department of Agriculture), he wrote, Mosquitoes: How They Live; How They Carry Disease; How They Are Classified; How They May Be Destroyed. In his writings, he made his case for the use of chemicals and according to those writings, the only way to kill the Anopheles mosquito, and thereby to protect and serve the citizenry, was to blanket the nation with a combustible hydrocarbon mist of kerosene.

The use of kerosene worked and after the Insecticide Act of 1910 was initiated, mosquito spraying became standard practice.

Howard didn’t stop there in his crusade to protect and serve. With the advent of WWI, he contacted the war department and let them know that their problems with mites, mosquitoes, and lice, which were epidemic in war zones, could be eliminated by enlisting entomologists, armed with chemical sprays, to “wage war against insect life”,

thus solidifying his importance to the war effort.  The Division of Entomology was given the go-ahead to expand their use of chemicals to include; benzene, carbolic acid, creosote, alkaline soaks, and sulfur baths. This expansion in chemical usage gave birth to “Medical Entomology”.

Leland Howard retired from public service, in 1927 and lived to see the United States become the “insecticide nation” he so diligently championed. When he died in 1950, DDT had replaced kerosene as the world’s mosquito killer of choice.

A brief history of insecticide development:

Before 1900, the chemical known as Paris Green, an inorganic compound (copper(II) acetate triarsenite or copper(II) acetoarsenite) was the poison of choice for the control of many agricultural pests, rodents, and for mosquito control.  It is a highly toxic emerald-green crystalline powder developed around 1775 by Carl Scheele.   Paris green was heavily sprayed by airplanes in Italy, Sardinia, and Corsica during 1944 and 1945 to control malaria.  Arsenic pesticides, of which Paris Green is one,  didn’t arrive in the United States until the 1860s and ended its reign in the 1980s, when it was banned from use because of high residual toxicity levels and health-related conditions, including cancer.  

The organic age of insecticides began in 1943 with the advent of DDT usage. DDT is a member of the organochlorine group of insecticides, a group that primarily acts against the insects’ central nervous system. Many chemicals in this group are now banned. After World War II, the use of DDT flourished. It produced spectacular results, not only in mosquito control but against a wide variety of insects.

Shortly after World War II, organophosphorous insecticides came into being. Early compounds in this group included malathion, TEPP, and parathion, which were used in 1948. In 1952, carbamate insecticides began to be used. Among the first compounds were Sevin® and Propoxur. Propoxur is an example of a carbamate used against mosquito adults.

By the late 1960s, The 1st generation pyrethroids (synthetically made by industrial methods, using pyrethrums (oils) from chrysanthemum flowers) were widely used, primarily because of their quick-knockdown properties and low mammalian toxicity. Late in the 1970’s, 2^nd generation pyrethroids (more resistant to degradation by light and air), were on the market.

“Insect growth regulators” (IGRs) mimic hormones that affect insect growth, but they have little effect on non-target animals.  Their use against mosquitoes began with the use of methoprene in the early 1970s.  These products and similar ones using bacteria, viruses, or other natural pest control agents are called “biorational” pesticides.

Today, there are a variety of products available on the market for the public and for professionals when it comes to mosquito control. Larvicides are chemicals designed to be applied directly to water to control mosquito larvae. Adulticides are used in fogging and spraying to control adult mosquitoes. Synergists are not toxic to the mosquitoes themselves, but they make adulticides more effective.

The United States has developed a Love/Hate relationship with insecticides and in the face of a growing human population, increased urbanization, and worldwide travel, the demand for insecticides and other pesticides will only become greater.

Here are facts about pesticide usage in the United States:

1. Pesticides are used on 900,000 farms and in 70 million households.
2. Herbicides are the most widely used type of pesticide.
3. Agriculture uses 75% of all pesticides.
4. 85% of all U.S. households have at least one pesticide in storage, and 63% have one to five stored.