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In 1954 Mexican fruit flies were discovered at several points in 

 northwestern Mexico near Tijuana, within a half-mile of the inter- 

 national boundary, and a single specimen was found in southern 

 California near the border (Harper 4). These discoveries created 

 an emergency need for expansion of the Mexican fruit fly program 

 being conducted at Mexico City, and the bioclimatic -cabinet studies 

 were initiated at the Pink Bollworm Research Center in November of 

 that year. Experiments are also being conducted to ascertain the 

 length of diapause or hibernation, rate of emergence, and mortality 

 of the pink bollworm in normally infested cotton bolls when exposed 

 to conditions of climate and environment found in widely separated 

 cotton-producing areas in the United States. The abilities of introduced 

 parasites and predators of the pink bollworm to establish themselves 

 under such conditions are also planned for investigation. 



In new cabinets set up at Brownsville several improvements were 

 incorporated, the most important of which were the introduction of 

 moisture in the form of steam, increased refrigeration capacity, 

 variable heat input, and exterior access to the air-handling units, 

 strip heaters, and blowers. 



Cabinet Construction 



The over -all dimensions of the cabinets (fig. 1), including the 

 refrigeration equipment and control panel, are 9 feet 7 1/2 inches by 

 11 feet 8 inches by 7 feet 7 1/4 inches high. They are of sectional 

 knockdown construction with 6 inches of fiber -glass insulation between 

 1/2 -inch layers of plywood, and an additional lining of 15 -pound vapor - 

 proof building paper backing the outer plywood layer. The upper layer 

 of the insulated floor is of 5/8 -inch plywood. The exterior of the cabinet 

 is painted with three coats of glossy white enamel, and the interior is 

 lined with stainless steel with all seams sealed. The floor is provided 

 with a single drain. The inner chamber is 6 feet square and 6 1/2 feet 

 high. 



One refrigerator -type door of construction similar to that of the 

 walls, with stainless -steel inner surface and an opening approximately 

 2 feet 6 inches wide and 5 feet 9 inches high, opens outward into an 

 anteroom. The anteroom measures 4 feet square, inside dimensions, 

 and is of the same height and construction as the main room. It is 

 equipped with an outer, heavy refrigerator door, similar to that used 

 in the inner chamber but without the stainless -steel lining. 



Opposite the door are two windows providing a total viewing sur- 

 face of 15 square feet. Each window consists of three noncondensing 

 Thermopanes 1/4 inch apart with the space between evacuated. 



