story in each instance) through a length of h-inch flexible duct which in 
turn discharged into an 18-inch duct. The aerosol formulation consisted of 
DDVP dissolved in 5 or 10 gallons of light hydrocarbon oil. A dosage rate of 
4.25 grams of DDVP per 1,000 cubic feet was applied to the type A warehouse 
and a rate of 8.5 grams per 1,000 cubic feet to the type B warehouse. Twelve 
coated glass microscope slides were placed in each warehouse at locations 
varying from 2 to 96 feet from the aisles and at heights varying from 0 to 1h 
feet above the floor, After application of the aerosol, these slides were 
examined under a microscope and the percentage coverage and range of particle 
sizes recorded. 
The emulsion spray was prepared from a concentrate containing 50 percent 
of DDVP, 30 percent of tetrachloroethylene, and 20 percent of an emulsifier, 
diluted in water to 1 percent DDVP. Forty gallons were applied to the ex- 
posed floor, walls, and the underside of the roof in 1 type B (ventilated) 
warehouse, which was the equivalent of 3.5 grams per 1,000 cubic feet of 
total warehouse space. 
The solution consisted of DDVP dissolved in carbon tetrachloride. Three 
gallons were sprinkled in the aisles of 2 type A (semiclosed) warehouses. 
Concentrations were 2.1 grams per 1,000 cubic feet in 1 warehouse and .25 
grams per 1,000 cubic feet in the other, 
Sets of 12 cages of adult cigarette beetles were placed in the free air 
spaces of each warehouse, Six were at floor level and 6 on top of the third 
tier of hogsheads. They were arranged in a horizontal pattern, with 3 cages 
about equidistant near the aisle, and 3 near the back wall. The cages were 
placed in the warehouses before and at intervals after application of the 
DDVP, and were exposed for 2) er 8 hours, as shown in table 1. 
One cage containing 2 male and 3 female white rats of the "Charles River" 
strain was placed in each warehouse during or immediately after applications 
of the DDVP, and left undisturbed for 7 days. 
Results 
The insect mortality results are given in table 1. All test insects 
were killed in warehouses of both types A and B at all application rates 
tested, when exposed during the first 2) hours after DDVP had been applied. 
All test insects exposed during the second or third 2) hours were killed in 
the type A (semiclosed) warehouses with application rates of .25 grams per 
1,000 cubic feet and above. Mortality was very low in type B (ventilated) 
warehouses, under these same conditions. One group of insects exposed for 2) 
hours, 7 days after application of .25 grams per 1,000 cubic feet, had a 
mortality of 85 percent in a type A warehouse. 
