The growing public concern about the exposure of humans to insecticides has led to increased efforts toward alternative management strategies. Today’s consumer wants safe, effective, easy-to-use products which give rapid, dependable control of insect pests. By comparison, some historic flea control techniques were quite hazardous, as well as time-consuming and laborious, especially compared with the total-release aerosols and other convenient products commonly used for flea control these days.
While the industry has developed procedures for limiting the exposure of humans to insecticides by selective applications, treatments for fleas, by necessity, cover large expanses of the home. Therefore, the quantities of chemical that must be applied indoors for flea control, especially when the entire floor area is carpeted, requires that the pest control industry address the questions of human and pet exposure, as well as chemophobia and allergic reactions to pesticides (Story 1986).
TREATMENTS IN THE HOME. The statement is still valid today that “cleanliness and basic sanitation are the foundations of good pest management programs” (Fernald & Shepard 1942). As is true of most pest problems, sanitation is a critical component of control, a point repeated inevitably in all recommendations for flea control. Bishopp (1921) pointed out that alternative hosts should be discouraged from the area, to prevent their serving as a source of infestation. He added that infestations in the home could be prevented by eliminating pet animals, removing rugs, thoroughly scrubbing the floors with soap and water, and then applying gasoline to the floors, “care being taken to avoid having fires about during the procedure.” Thorough cleaning is essential to remove the larval food, and all floor coverings should be regularly removed and cleaned, such as airing and beating rugs (Fernald & Shepard). In the past, alum was used, both in the powdered form sprinkled over carpets and rugs and by dipping papers in an alum solution and placing them under the rugs (Bishop 1921). Riley and Johannsen (1915) suggested the thorough sweeping of houses at frequent intervals, and keeping the floors as bare as possible.
Ewing (1929) recognized the significance of flea development in the bedding of the animal, saying that “if dogs or cats are allowed to sleep in the house, they should be given a mat or rug to lie upon. This mat should be regularly taken out and shaken and left for a few hours in the sun.”
Fumigation with various compounds has been used for flea control. A common practice prior to discovery of the chlorinated hydrocarbons was the use of flake napthalene at the rate of five pounds per room scattered over the floor of an infested room, with the doors and windows tightly closed for 24 hours (Fernald & Shepard). O’Kane (1912) claimed that this would rid a room of adult fleas but had little effect on eggs.
Matheson (1932) recommended that “in houses, public buildings, ships, etc. heavily infested with fleas the best procedure is fumigation with hydrocyanic acid gas.” This practice seems extreme to us today.
The logistics of fumigation with sulfur become daunting when one realizes that according to the instructions given by Bishopp (1915), the average 2,000-square-foot home would require 64 pounds of sulfur for adequate fumigation, and the structure would have to be vacated for at least 12 hours. This corrosive gas can also cause damage to metal objects.
A light infestation in the home was controlled by thorougly treating with pyrethrum or rotenone sprays or dusts. Cracks were soaked with kerosene or gasoline (Ewing). Cellars were cleaned and whitewashed (Fernald & Shepard), and scrubbed occasionally with hot soapy water, “preferably medicated with some carbolic acid” (Riley & Johannsen).
OUTDOOR TREATMENTS. Salt has historically been used as a desiccant in areas where immature fleas are developing, by scattering salt on the area dry (Metcalf & Flint 1939), or then wetting it down thoroughly (Bishopp 1921, Furman 1971). Near the coast, soil around runways and kennels was treated with seawater (Ewing). As salt is an indiscriminate herbicide, however, its use is limited to areas without vegetation.
Outdoors it was shown that “very striking results” might be accomplished by the spraying of an infested area, whether in a basement, chicken house, barn or feed lot, with creosote oil. A light spraying was said to kill the adult fleas almost instantly and also to have some destructive affect on the immature stages (Bishopp 1921). For out-buildings, Matheson recommended cleaning thoroughly, then spraying with kerosene or crude petroleum.
For on-animal control of fleas, Fernald & Shepard recommended dusting pets with derris powders or washing with derris soaps. Matheson suggested rubbing finely powdered napthalene, buhach, or pyrethrum into the fur, saying “these substances stupefy the fleas and as they drop on sheets of paper may be collected and burned.” Bishopp (1915) described the use of napthalene for on-animal use, pulverizing moth balls and working the powder into the animal’s fur. Unfortunately, the treatment “slightly sickened the cats for two days,” making it an unattractive option.
Ewing added that in addition to dusting dogs with pyrethrum or other insect powders, the animal “should be bathed frequently in warm water using a medicated soap, such as carbolic acid soap.” Bishopp (1921) also championed the need for washing the pet, suggesting the use of “a comparatively weak solution of saponified creosote or kerosene emulsion.” Both authors urged caution with these substances, noting that they were all caustic and could only be used in very diluted forms.
For sticktight fleas on chickens, Bishopp (1915) recommended a mixture of one part kerosene to three parts lard applied to the affected parts of the animal — warning that it would prove injurious if used too freely.
Commenting on the dramatic change in pest control strategies which ensued with the discovery of the insecticidal properties of chlorinated hydrocarbons following World War II, Brown (1951) wrote “whereas before fleas were controlled by application of pyrethrum and rotenone dusts and dips to the body and thiocyanate sprays to the habitation, with DDT, applications of dusts or sprays could be made to the animal as well as the home.” DDT and its relatives were so effective against household pests, and so safe to humans and pets, that control programs essentially relied on them to the virtual exclusion of habitat modification, mechanical control, sanitation, etc. The loss of these compounds, either because of their environmental hazards or the reduction in effectiveness due to the development of resistance, led to the eventual use of the organophosphates, carbamates, pyrethroids, etc. in the struggle against fleas.
Dr. Nancy Hinkle is a state extension veterinary entomologist with the University of California- Riverside.
Bishopp, F.C. 1915. Fleas. U.S.D.A., Bull. No. 248. 31 pp.
Bishopp, F.C. 1921. Fleas and their control. Farmers’ Bulletin 897, U.S.D.A. 16 pp.
Brown, A.W.A. 1951. Insect Control by Chemicals, John Wiley & Sons, London. pp. 685-686.
Ewing, H.E. 1929. A Manual of External Parasites, Charles C. Thomas, Baltimore, Md. 225 pp.
Fernald, H.T. 1942. Applied Entomology: An Introductory Textbook of Insects in Their Relations to Man, 4th Edition, McGraw-Hill, New York. pp. 331-334
Furman, D.P. 1971. Poultry insects and related pests. In R.E. Pfadt (ed.) Fundamentals of Applied Entomology, Macmillan Publ. Co., New York. pp. 589-610.
Matheson, R. 1932. Medical Entomology. Charles C. Thomas Publ., Baltimore, Md. 489 pp.
Metcalf, C.L. & W.P. Flint. 1939. Destructive and Useful Insects: Their Habits and Control, 2nd Edition. McGraw-Hill, New York. 981 pp.
O’Kane, W.C. 1912. Injurious Insects: How to Recognize and Control Them. Macmillan Publ. Co., New York. 414 pp.
Riley, W.A. & O.A. Johannsen. 1915. Handbook of Medical Entomology. Comstock Publ. Co., Ithaca, N.Y. 348 pp.
Story, K. 1986. A PCO’s guide to flea control. Pest Control Technology 14(7): 46-50.
Sidebar: A Timeline of Flea Control Treatments in the U.S.
1910: sanitation; fumigation with sulfur or flake napthalene; pet application of pulverized napthalene; pyrethrum dusts applied to indoor/outdoor surfaces and pets
1930: sanitation; treatment of pet, surfaces with carbolic acid; treatment of surfaces with pyrethrum or rotenone sprays; fumigation with hydrocyanic acid gas; application of alum, gasoline, kerosene, crude petroleum or creosote oil to floors; application of salt inside and outside the home
1950: sanitation; DDT application to the pet and home, inside and out; pyrethrum applications
1970: sanitation; treatment of the home surfaces, inside and out with organophosphates, carbamates, or pyrethroids
1990: sanitation; treatment of pet and indoor surfaces with the IGRs; treatment of indoor/outdoor surfaces with carbamates, organophosphates, or pyrethroids