NO. I BLACK FLIES OF GUATEMALA — DALMAT 5 



borne, carried from 20 to 90 miles from the breeding places. Although 

 the animals affected included cattle, horses, sheep, hogs, and others, 

 more than 80 percent of the 800 animals killed were cattle. At times 

 the animals started dying within 4 hours after attack by the flies. In 

 the few outbreaks mentioned above and in others described in accounts 

 of various authors (Webster, 1904; Wilhelmi, 1920; Bradley, 1935), 

 it appears that deaths usually occur as a consequence of an acute 

 toxemia, caused by the vast number of bites of black flies, or as a 

 result of anaphylactic shock. Debility, due to a heavy loss of blood, 

 and suffocation brought about by inhalation of myriad flies may also 

 be contributing factors. 



Black flies are not only pests of domestic and wild animals in the 

 Western Hemisphere, but their attack on man has prevented the 

 normal exploitation of highly desirable areas in the United States and 

 Canada. With the application of modern control techniques, it has 

 been found economically feasible to develop some of these regions 

 into resort areas, as well as to construct strategic roads and bases (e.g., 

 Alaska Highway). 



In Guatemala, the Merck & Co. quinine plantation, Finca Monte- 

 quina (Municipality of Atitlan, Department of Solola), was so badly 

 infested by anthropophilic species of black flies during February 1948 

 that workers were threatening to leave the finca employ. The flies 

 were a pest not only in the fields but in the buildings as well. Many of 

 the workers were suffering from edema, pruritus, lymphangitis, and 

 fever brought on by the bites. Several had developed secondary in- 

 fections from scratching bites that caused intense itching. The author 

 was consulted for help in alleviating the plague. Finca Montequina, 

 comprising 564 acres, is situated on the southwest slope (facing the 

 Pacific Ocean) of the Volcano Atitlan, at an altitude of 3,200 feet. 

 That part of the plantation on which the workers were especially 

 exposed to the ravages of the fly population is situated on one of the 

 ridges exposed to the Pacific winds. After an unsuccessful attempt 

 to find probable breeding areas of the flies in the vicinity of the finca, 

 it was determined that they had been carried into the region by mon- 

 soons prevailing at that season of the year. With the application of 

 DDT to the region infested and to the dwellings therein situated, and 

 with the fortunate cessation of the winds, the fly problem was 

 markedly reduced. 



Another finca, Santa Emilia, located at 3,560 feet in the Munici- 

 pality of San Pedro Yepocapa, Department of Chimaltenango, is situ- 

 ated on the Pacific slopes of the Volcanoes Fuego and Acatenango. 

 The flies were so numerous, and the biting so constant during January 



